An emission processing system for air quality modelling in the Mexico City metropolitan area: Evaluation and comparison of the MOBILE6.2-Mexico and MOVES-Mexico traffic emissions.

This article describes the High-Elective Resolution Modelling Emission System for Mexico (HERMES-Mex) model, an emission processing tool developed to transform the official Mexico City Metropolitan Area (MCMA) emission inventory into hourly, gridded (up to 1km2) and speciated emissions used to drive mesoscale air quality simulations with the Community Multi-scale Air Quality (CMAQ) model. The methods and ancillary information used for the spatial and temporal disaggregation and speciation of the emissions are presented and discussed. The resulting emission system is evaluated, and a case study on CO, NO2, O3, VOC and PM2.5 concentrations is conducted to demonstrate its applicability. Moreover, resulting traffic emissions from the Mobile Source Emission Factor Model for Mexico (MOBILE6.2-Mexico) and the MOtor Vehicle Emission Simulator for Mexico (MOVES-Mexico) models are integrated in the tool to assess and compare their performance. NOx and VOC total emissions modelled are reduced by 37% and 26% in the MCMA when replacing MOBILE6.2-Mexico for MOVES-Mexico traffic emissions. In terms of air quality, the system composed by the Weather Research and Forecasting model (WRF) coupled with the HERMES-Mex and CMAQ models properly reproduces the pollutant levels and patterns measured in the MCMA. The system's performance clearly improves in urban stations with a strong influence of traffic sources when applying MOVES-Mexico emissions. Despite reducing estimations of modelled precursor emissions, O3 peak averages are increased in the MCMA core urban area (up to 30ppb) when using MOVES-Mexico mobile emissions due to its VOC-limited regime, while concentrations in the surrounding suburban/rural areas decrease or increase depending on the meteorological conditions of the day. The results obtained suggest that the HERMES-Mex model can be used to provide model-ready emissions for air quality modelling in the MCMA.

Low grade radiographic sacroiliitis as prognostic factor in patients with undifferentiated spondyloarthritis fulfilling diagnostic criteria for ankylosing spondylitis throughout follow up.

OBJECTIVE: To determine the rate and factors associated with ankylosing spondylitis in a cohort of patients with undifferentiated spondyloarthritides (SpA). METHODS: 62 consecutive patients with undifferentiated SpA seen between 1998 and 1999 underwent clinical and imaging evaluations throughout follow up. The main outcome measure was a diagnosis of ankylosing spondylitis. RESULTS: 50 patients with peripheral arthritis (n = 35) and inflammatory back pain (n = 24) (26 male; mean (SD) age at onset, 20.4 (8.8) years; disease duration 5.4 (5.7) years) were followed up for 3-5 years. At baseline, >90% of patients had axial and peripheral disease, while 38% had radiographic sacroiliitis below the cut off level for a diagnosis of ankylosing spondylitis (BASDAI 3.9, BASFI 2.9). At the most recent evaluation, 21 patients (42%) had ankylosing spondylitis. Two factors were associated with a diagnosis of ankylosing spondylitis in multivariate analysis: radiographic sacroiliitis grade <2 bilateral, or grade <3 unilateral (odds ratio (OR) = 11.18 (95% confidence interval, 2.59 to 48.16), p = 0.001), particularly grade 1 bilateral (OR = 12.58 (1.33 to 119.09), p = 0.027), and previous uveitis (OR = 19.25 (1.72 to 214.39), p = 0.001). Acute phase reactant levels, juvenile onset, and HLA-B27 showed a trend to linkage with ankylosing spondylitis (NS). CONCLUSIONS: Low grade radiographic sacroiliitis is a prognostic factor for ankylosing spondylitis in patients originally classified as having undifferentiated SpA. Low grade radiographic sacroiliitis should be regarded as indicative of early ankylosing spondylitis in patients with undifferentiated SpA.

Hemodynamic performance in-vivo of a new ventricular assist device.

Nowadays, circulatory support has become a common practice in medicine and a standard in the treatments of Cardio Vascular Disease (CVD). A new Pneumatic Ventricular Assist Device (VAD) has been developed in México City. This paper shows the first results of acute in-vivo trials, intended to verify the new system for providing physiological flows and pressures. Two VADs were implanted to as right (RVAD), left (LVAD) support in a 65 kg pig. The support time was 20 minutes with RVAD, 20 minutes with LVAD and 20 minutes with Biventricular (BiVAD). The VAD proved its capability to maintain physiological parameters during the support time. We are satisfied with the results of this trial, and we believe this study will ascertain the first step on the next phase of invivo trials.

Relationship between disease activity and infection in patients with spondyloarthropathies.

OBJECTIVE: To assess the relationship between disease activity and signs and symptoms of infection in Mexican patients with spondyloarthropathies (SpA). METHODS: A cross sectional study of 95 non-selected patients with SpA (62 men; mean age 26.4 years), who were examined for signs and symptoms of infection and their association with disease activity. 52 had ankylosing spondylitis (AS), 32 undifferentiated SpA (uSpA), 6 chronic reactive arthritis (ReA), and 5 psoriatic arthritis (PsA). Categorical data were analysed by chi(2) or Fisher's tests. RESULTS: 53 (56%) patients had infections: 41 (43%) upper respiratory tract (URT), 34 (36%) enteric, and 20 (21%) genitourinary infections. More infections occurred in HLA-B27 positive patients as a whole (39 v 5; p = 0.003) and in uSpA (12 v 2; p = 0.005). In AS and uSpA, infections occurred in approximately 50%. 30/39 (77%) patients with active disease (group A) and 23/56 (41%) (group B) (p = 0.001) had infection. There were more enteric infections in group A (47%; p<0.001) and more URT infections in group B (52%; p = NS). 22/30 (73%) patients attributed disease activity to infection. CONCLUSION: Enteric, and less commonly, URT infections in Mexican patients with SpA, particularly those who were HLA-B27 positive, seem to have a role in the active phase of AS and uSpA.

Cytokine correlates of clinical response patterns to infliximab treatment of ankylosing spondylitis.

OBJECTIVE: To identify clinical and immunological markers of response to treatment with infliximab in ankylosing spondylitis (AS). METHODS: Baseline and sequential cytokine levels (IL1, TNFalpha, IFNgamma, TGFbeta and IL10) were examined after 52 weeks of infliximab treatment 5 mg/kg in 22 patients. RESULTS: At week 52, 18 patients were responders and four non-responders according to ASAS group criteria. Clinical measures of disease activity between the two groups at baseline were similar, apart from a trend towards longer disease duration in non-responders (p = 0.08). Baseline CRP and TNFalpha levels were higher in responders than non-responders (p<0.01 and p<0.006, respectively). The two groups had similar baseline cytokine levels, apart from TNFalpha. Baseline CRP levels did not correlate significantly with baseline cytokine levels in responders, but a strong correlation was noted between baseline CRP and IL1, IFNgamma, and IL10 in non-responders. Apart from an early rise in TGFbeta and a decrease in IL10 in responders after the first infusion, sequential cytokine analysis for the first six months of treatment was not related to clinical disease activity measures. CONCLUSION: Although sequential cytokine analysis does not appear to be informative, baseline CRP and TNFalpha levels are useful markers of clinical response patterns in patients with AS treated with infliximab.

Comparative immune responses to candidate arthritogenic bacteria do not confirm a dominant role for Klebsiella pneumonia in the pathogenesis of familial ankylosing spondylitis.

OBJECTIVE: Using humoral immune responses, Klebsiella pneumoniae has been implicated as a candidate microbial trigger in ankylosing spondylitis (AS) by several investigators but refuted by others. The objective of this case-control study was to compare the cellular (T-cell proliferation) and humoral (IgG and IgA, by ELISA) immune responses of affected individuals in multiplex AS families with those of unaffected family members and normal healthy controls in order to find out whether affected individuals exhibit a predominant immune response to K. pneumoniae. METHODS: Twenty-five families with two or more individuals affected with AS and 34 normal healthy controls matched with the affected family members for age, sex and ethnicity were enrolled in the study. All affected (n = 57) and unaffected (n = 37) family members had a detailed clinical evaluation. Peripheral blood was drawn to determine T-lymphocyte proliferation and the IgG and IgA (by ELISA analysis) immune responses to K. pneumoniae, Salmonella typhimurium, Yersinia enterocolitica and Chlamydia trachomatis. Immune responses to each of the four candidate organisms were compared in affected and unaffected individuals. Each individual was classified by the predominant antigenic immune response that they showed when comparison was made among the same concentrations of the four candidate microbial antigens. This stratification was then used (i) to compare immune responses in affected and unaffected family members and (ii) to compare clinical characteristics of affected family members. RESULTS: There was no difference in mean stimulation indices or antibody responses between affected and unaffected family members for each of the candidate organisms. In terms of predominant cellular immune responses to these organisms, there was no difference between affected and unaffected family members with respect to K. pneumoniae, C. trachomatis or Y. enterocolitica. However, a higher percentage of affected family members (25.9%) exhibited a predominant response to S. typhimurium compared with unaffected family members (5.9%, P < 0.02). In assessing antibody titres, K. pneumoniae was the predominant amongst these four organisms, but there was no difference between affected family members, unaffected family members and normal healthy controls. There was no relationship between immune responses and clinical characteristics. CONCLUSION: Our analysis of affected and unaffected family members in familial AS demonstrated no significant differences with respect to cellular or humoral immune responses to K. pneumoniae and three control microbes. In addition, K. pneumoniae did not exhibit a predominant immune response in affected individuals. Thus we find no supportive evidence to implicate a causal role for K. pneumoniae in familial AS.

Translation, cross-cultural adaptation, and validation of the Bath Ankylosing Spondylitis Functional Index (BASFI), the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Dougados Functional Index (DFI) in a Spanish speaking population with spondyloarthropathies.

OBJECTIVES: The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), the Bath Ankylosing Spondylitis Functional Index (BASFI) and the Dougados Functional Index (DFI) are the most commonly used instruments to measure disease activity and functioning in ankylosing spondylitis (AS). The aim of this study was to translate, adapt and validate these instruments into the Spanish language. METHODS: The BASDAI, BASFI, and DFI questionnaires were translated into Spanish by three independent bilingual physicians who were familiar with the medical aspects of AS and by one professional translator. Two rheumatologists familiar with instrument validation, and who were aware of the purpose of the study, examined semantic, idiomatic and conceptual issues and produced by consensus unified versions of each instrument. English back-translations from the Spanish were done by a professional translator unaware of the original version. Both English versions were compared, and where needed, modifications to the Spanish versions were made. The Spanish versions were administered to 61 ambulatory patients with AS and to 80 patients with undifferentiated spondyloarthropathy for validation purposes. Reliability and responsiveness were measured in 28 patients participating in a physiotherapy program. RESULTS: Reliability showed an acceptable 24-hour test-retest intraclass correlation coefficient (ICC)--BASFI ICC: 0.68, 95% CI: 0.29-0.85; BASDAI ICC: 0.74, 95% CI: 0.52-0.88 and DFI ICC: 0.87, 95% CI: 0.73-0.94. The construct validity of the instruments was evaluated, and BASDAI was correlated with disease activity measured by the total enthesis count (rs: 0.34); general well being in the last week (rs: 0.7); spinal pain (rs: 0.53) and duration of morning stiffness (rs: 0.64). BASFI correlated with Schöber's test (rs: -0.4); occipital-wall distance (rs: 0.38) and thoracic expansion (rs: -0.3). DFI correlated with Schöber's test (rs: -0.36); occipital-wall distance (rs: 0.29) and chest expansion (rs: -0.3). The correlation among DFI and BASFI was rs: 0.83. All instruments showed clinical responsiveness in the physiotherapy program (baseline and end of program; mean +/- SD): BASDAI: 6.25 +/- 1.97 and 3.07 +/- 2.04 (p = 0.0001); BASFI: 5.68 +/- 2.29 and 2.88 +/- 1.77 (p = 0.0001); DFI: 16 +/- 7.6 and 8.0 +/- 5.5 (p = 0.001) with effect sizes and standardized effect sizes > 1. CONCLUSIONS: The Mexican Spanish versions of the BASDAI, BASFI, and DFI showed adequate reliability, validity and responsiveness to clinical change. These instruments can be used in the clinical evaluation of Spanish-speaking patients with AS.

A short-term follow-up of enthesitis and arthritis in the active phase of juvenile onset spondyloarthropathies.

OBJECTIVE: To describe the characteristics of enthesitis and arthritis in the active inflammatory stage of juvenile onset spondyloarthropathies (SpA) during a short-term follow-up. PATIENTS AND METHODS: The study group included data of 33 patients with juvenile-onset SpA with enthesitis in > or = 3 sites, arthritis in > or = 4 joints, and erythrocyte sedimentation rate (ESR) of > or = 25 mm/h despite treatment, who participated in a 26-week, double-blind, sulfasalazine versus placebo trial that showed no significant differences between groups in regard to enthesitis and arthritis. RESULTS: Twenty-seven boys and 6 girls (mean age: 15.3 +/- 3.5 years; mean disease duration: 4.1 +/- 2.7 years) with the seronegative enthesopathy and arthropathy (SEA) syndrome (n = 20) or ankylosing spondylitis (AS; n = 13) comprised the group. Throughout the study, the mean (+/- SD) number of swollen joints and tender entheses were 4.6 +/- 2.5 and 8.3 +/- 5.4. The entheses and joints most frequently involved were the calcaneal attachments of the plantar fascia (87.9%) and Achilles tendon (81.8%) and the ankle (87.9%) and knee (72.7%), respectively. There was pain in the cervical, thoracic, and lumbar spine in 39.4%, 69.7%, and 63.6% of patients and in the sacroiliac joints in 48.5%. Mid-foot involvement (or tarsitis) occurred in 29 patients (87.9%). Except for the feet, the simultaneous occurrence of enthesitis and arthritis in other sites was rare. Overall, there were no significant differences between SEA syndrome and AS patients. CONCLUSIONS: Disease activity shows a significant trend for entheses and joints of the feet and a significant prevalence of axial enthesitis in juvenile onset SpA. Mid-foot involvement appears to be the most characteristic and potentially, the most severe form of disease in these patients.

Effect of HLA-B and HLA-DR genes on susceptibility to and severity of spondyloarthropathies in Mexican patients.

OBJECTIVE: To investigate the role of HLA-B and HLA-DR genes as contributors to genetic susceptibility and clinical expression of the spondyloarthropathies (SpA) in the Mexican population. METHODS: The study included 172 patients with SpA (undifferentiated SpA 83, ankylosing spondylitis (AS) 64, and reactive arthritis 25) and 99 healthy controls. The HLA-B and HLA-DR alleles were detected by the polymerase chain reaction with sequence-specific primers technique. Patient assessment included demographic data, diagnostic categories, and disease patterns. Statistical methods included the Mantel-Haenzel chi(2) test, Fisher's exact test, and Woolf method for odds ratio (OR). Differences of continuous variables between HLA allele groups were calculated by Student's t test. RESULTS: Increased frequencies of HLA-B27 (pCh10(-3), OR=28.7), HLA-DR1 (pC=0.045, OR=2.77), and HLA-B15 (p=0.034, pC=NS, OR=2.04) alleles in the whole group were found. HLA-B27 strength of association (OR) was 41.4 in AS; 20.9 in undifferentiated SpA; 27.2 in reactive arthritis. HLA-DR1 and HLA-B15 were increased in undifferentiated SpA (pC=0.045, OR=2.98 and p=0.004, pC=NS, OR=2.75). By analysing 58 HLA-B27 negative patients it was found that HLA-B15 and HLA-DR1 associations with SpA were independent of HLA-B27; increased frequencies of HLA-B15 were found in the whole SpA group and in patients with undifferentiated SpA (pC=0.03, OR=3.09 and pCh0.01, OR=3.77) and of HLA-DR1 in the latter (p=0.04, pC=NS, OR=3.15). HLA-B27 positive patients were younger than HLA-B27 negative patients at onset (p=0.03), but HLA-DR1 positive patients were older than HLA-DR1 negative patients (p=0.03). Bath indices for disease activity and functioning were higher in HLA-B27 positive patients (p=0.006 and p=0.004 v HLA-B27 negative patients). In contrast, neither HLA-DR1 nor HLA-B15 influenced these indices. CONCLUSION: Apart from HLA-B27, there is a significant association of HLA-DR1 and HLA-B15 with SpA in Mexicans which is independent of B27. HLA-B27 is associated with younger age at onset and increased disease severity and HLA-DR1 with older age at onset. The strength of HLA-B15, HLA-B27, and HLA-DR1 associations varied in different forms of SpA.

Development of a radiographic index to assess the tarsal involvement in patients with spondyloarthropathies.

OBJECTIVE: To develop and test an index to evaluate the radiographic changes that occur in the tarsus and adjacent areas of the foot in patients with spondyloarthropathies (SpA). METHODS: The spondyloarthropathy tarsal radiographic index (SpA-TRI) was developed in three consecutive steps: (a) detection of descriptors after reviewing 70 radiographic files; (b) descriptor gradation and subsequent modifications performed by a consensus committee, and (c) interobserver variability assessed by three blinded and independent observers on 272 radiographs: anteroposterior 118, lateral 90, oblique 64 from 121 patients with SpA, and intraobserver variability on 75 radiographs from 25 patients with SpA. Statistical analysis included percentage of agreement and kappa test. SpA-TRI score ranges from 0 to 4 (0=normal; 1=osteopenia or suspicious findings; 2=definite joint space narrowing, bony erosion(s), periosteal whiskering, or enthesophyte(s) in the plantar fascia or Achilleal tendon attachments; 3=para-articular enthesophyte(s); 4=bony ankylosis (joint space fusion or complete bridging)). RESULTS: Complete agreement for every evaluation was >40%, and discordance >1 grade was <15%. The kappa scores among the three observers were acceptable for all the single projections: oblique (0.52, 0.36, 0.35), lateral (0.50, 0.42, 0.56), and anteroposterior (0.40, 0.41, 0.21) views. The combination of lateral and oblique views achieved the highest concordance rates (0.72, 0.33, 0.66), surpassing that of the three projections altogether (0.34, 0.58, 0.37). In every case the concordance was comparable with that of sacroiliac joints (0.47, 0.41, 0.34); intraobserver concordance showed a similar trend. CONCLUSION: The SpA-TRI is an index that includes the most prominent features of tarsal disease and adjacent areas of the foot in SpA and grades them accordingly, it has an adequate reproducibility, and is suitable for use with two or more projections, preferably the combination of oblique and lateral.

Heat shock protein 70 gene polymorphisms in Mexican patients with spondyloarthropathies.

OBJECTIVE: To investigate the role of HSP70 genes as contributors to genetic susceptibility of the spondyloarthropathies (SpA) in the Mexican population. METHODS: The study included 150 patients with SpA (undifferentiated spondyloarthropathy (uSpA) 68, ankylosing spondylitis (AS) 60, and reactive arthritis 22) and 158 healthy controls. HSP70-1, HSP70-2 and HSP70-hom genotypes were analysed by the polymerase chain reaction-restriction fragment length polymorphism technique. Statistical methods included the Mantel-Haenzel, chi(2), Fisher's exact test, and Woolf's method for odds ratio (OR). RESULTS: HSP70-2 B/B genotype frequency was increased in the whole group of patients with SpA (pC<0.05, OR=4.3), as well as in the different clinical subgroups (pC<0.05, OR=4.2 for AS; pC<0.05, OR=4.4 for uSpA; and pC<0.05, OR=4.1 for ReA). This frequency remained significantly increased when the patients with B27 negative SpA were analysed. On the other hand, HSP70-hom locus analysis showed significantly increased frequency of A allele in the whole group of SpA (pC<0.05, OR=3.4), as well as in the groups with AS (pC<0.05, OR=5.6) and with uSpA (pC<0.05, OR=3.1), when compared with healthy controls. In this case, also, the genotype A/A was increased in the whole group of SpA (pC<0.05, OR=4.5), as well as in patients with AS (pC<0.05, OR=6.4) and with uSpA (pC<0.05, OR=3.7). When the patients with B27 negative SpA were analysed the frequencies of HSP70-hom A allele and A/A genotype remained significantly increased in the whole group of SpA (pC<0.05, OR=3.2 for the A allele and pC<0.05, OR=4.2 for the A/A genotype) and in the uSpA subgroup (pC<0.05, OR=3.8 for the A allele and pC<0.05, OR=4.3 for the A/A genotype). CONCLUSION: In addition to the association of SpA with HLA-B27, there is a significant association of HSP70-2 and HSP70-hom alleles with SpA in Mexicans. This association seems to be independent of the susceptibility conferred by HLA-B27 in the group of patients with uSpA.

Relation between adverse events associated with allopurinol and renal function in patients with gout.

BACKGROUND: Because serious adverse reactions to allopurinol have been related to a reduce creatinine clearance rate and prolonged half life of oxypurinol, it has been recommended that the dose should be adjusted according to the rate of creatinine clearance. However, in some patients with gout the dose is not sufficient to reduce serum levels of uric acid (< or =390 micromol/l) and to halt disease progression. OBJECTIVE: To determine the prevalence of adverse reactions attributable to allopurinol in patients with primary gout according to dose and creatinine clearance rate. METHODS: Data on 120 patients with gout receiving allopurinol, in whom the starting dose was adjusted according to creatinine clearance rate and later increased in some patients to control the disease, were retrospectively reviewed. Two groups were compared: group A, 52 patients receiving creatinine clearance adjusted maintenance doses of allopurinol and group B, 68 patients receiving non-adjusted higher maintenance doses of allopurinol. RESULTS: During follow up 57% required higher allopurinol doses than those recommended according to their creatinine clearance rate. Only five (4%) of 120 consecutive patients developed allopurinol related adverse reactions: four minor skin reactions and one allopurinol hypersensitivity syndrome (AHS). Three of these (including the case of AHS) occurred in group A and two in group B (p=NS). The duration of allopurinol treatment was the same in both groups (group A: 2.3 (3.3) years; group B: 3.7 (4.8) years). No patient in group A, but 44% in group B had a creatinine clearance rate of <50 ml/min. None of the patients received concomitant diuretics, ampicillin, or azathioprine. CONCLUSIONS: No increase was seen in the prevalence of adverse reactions to allopurinol in patients who received higher allopurinol maintenance doses than those recommended according to creatinine clearance rate.

Bacterial DNA in synovial fluid cells of patients with juvenile onset spondyloarthropathies.

OBJECTIVE: To identify bacterial DNA in synovial fluid cells of patients with active juvenile onset spondyloarthropathy (SpA). METHODS: The main group of study constituted 22 patients with juvenile onset SpA. In addition, five patients with adult onset SpA and nine with rheumatoid arthritis (RA) were studied. Polymerase chain reaction (PCR) with either genus- or species-specific primers was performed on synovial fluid cells to detect DNA sequences of Chlamydia trachomatis, Yersinia enterocolitica, Salmonella sp., Shigella sp., Campylobacter sp. and Mycobacterium tuberculosis. The presence of antibacterial antibodies in sera and synovial fluid was also determined by enzyme-linked immunoassay. RESULTS: The synovial fluid of nine patients with juvenile onset SpA, three with adult onset SpA and one with RA contained bacterial DNA. Five juvenile onset SpA samples had DNA of one single bacterium; two juvenile onset SpA and three adult onset SpA had DNA of two bacteria and two juvenile onset SpA had DNA of three bacteria. Overall, Salmonella sp. DNA was detected in seven synovial fluid samples, Shigella sp., Campylobacter sp. and M. tuberculosis were found in four samples each, and C. trachomatis was found in two. The bacterial DNA findings correlated with neither diagnosis nor disease duration. One RA synovial fluid had DNA of Campylobacter sp. Neither serum nor synovial fluid antibacterial antibodies correlated with DNA findings or clinical diagnosis. CONCLUSION: In this study, single and several combinations of bacterial DNA were identified in the synovial fluid of patients with long-term undifferentiated and definite juvenile onset SpA and adult onset SpA. Of relevance is that bacterial DNA corresponds to bacteria producing endemic disease in our population.

The changes in leg blood flow during and after mild or severe acute hypoxaemia in healthy humans.

The present study examines the leg blood flow changes in resting healthy humans during and after a 10-min period of mild (PaO2=5.60 kPa) or severe hypoxaemia (PaO2=4.53 kPa) induced by breathing hypoxic gas mixtures. A Colour Duplex Scan system allowed to measure the cross-sectional area (CSA) and mean blood flow (Q) in a femoral artery (FA) and a femoral vein (FV) and also in an artery supplying leg muscles (medial gastrocnemius artery, MGA). During the mild as well as the severe hypoxaemia and their recovery periods, no significant variations of Q and CSA occurred in FA and FV. During the mild hypoxaemia and the first 10 min of the recovery period, Q and CSA of MGA increased (maximal changes: +84 and +20%, respectively). By contrast, a marked Q decrease and a reduced CSA were measured in MGA during the severe hypoxaemia (-67 and -60%, respectively). This reduced muscle blood flow was followed by a vasodilatation (CSA increase = +30%), which began 10 min after the hypoxaemia ended and persisted for a further 10-min period. This study shows that the time course of muscle blood flow changes in response to acute hypoxaemia depends on the PaO2 level. Reverse effects were measured during the mild or the severe hypoxaemia, whereas a post-hypoxaemic vasodilatation occurred in all circumstances.

Comparison of two schedules for administering oral low-dose methotrexate (weekly versus every-other-week) in patients with rheumatoid arthritis in remission: a twenty-four week, single blind, randomized study.

OBJECTIVE: To compare the efficacy of 2 low-dose oral methotrexate (MTX) schedules in maintaining remission in patients with rheumatoid arthritis (RA). METHODS: Patients with RA were included if they were receiving treatment with weekly MTX for at least 9 months and the RA was in remission (defined by American College of Rheumatology [ACR] criteria) for at least 6 months. Patients were stratified by treatment and randomly assigned to weekly or every-other-weekly (EOW; reducing their monthly dose by half) treatment with MTX. Patients were evaluated by a rheumatologist (blinded to the treatment schedule) at baseline and at 6, 12, and 24 weeks. The evaluations included joint counts, Ritchie Articular Index, Health Assessment Questionnaire Disability Index, physician's and patient's global health assessments, visual analog scale for pain, and incidence of adverse effects. Laboratory evaluations were done at baseline and at week 24. RESULTS: Fifty-one patients were included (26 taking weekly MTX, 25 taking EOW MTX). Baseline comparisons showed no differences between the groups. The mean duration of RA was <3 years in both groups, and they had been started on weekly MTX treatment early after diagnosis. After 24 weeks, >90% of the patients in both groups continued in remission. Evaluations of disease activity at 6 and 12 weeks showed no between-group differences. EOW MTX patients who experienced relapse were switched back to weekly MTX, and after a few weeks, their RA was again controlled. The incidence of adverse effects was slightly higher in the weekly MTX group, although the difference did not reach statistical significance. The observed laboratory values were very similar for both groups, except for the serum aspartate aminotransferase and alanine aminotransferase levels, which decreased in the EOW MTX group and were statistically significant at week 24 (P = 0.04 and P = 0.006, respectively). CONCLUSION: EOW MTX represents a valid therapeutic alternative for a specific subgroup of RA patients, as outlined by the ACR remission criteria. Patients with a short disease duration who were treated early after disease onset with weekly MTX and who achieve sustained remission have a higher probability of success with the EOW MTX schedule.

A proposal for the classification of patients for clinical and experimental studies on reactive arthritis.

OBJECTIVE: To propose classification criteria for patients entering clinical and basic studies on reactive arthritis (ReA). METHODS: From a MEDLINE search of articles published between 1980 and 1996, we identified reports on HLA-B27 related ReA and Reiter's syndrome as study groups and analyzed the items that constituted the diagnostic, classification, and inclusion (or entry) criteria of patients. We developed disease categories that constituted our classification proposal. RESULTS: We reviewed 175 articles containing 110 study groups of patients with ReA and 94 with Reiter's syndrome. Most articles (89.7%) relied on arthritis for diagnosis, but only 48.0% relied on infection. Only 22.5% of articles used published criteria for diagnosis. Articles including a bacterial name to further describe a group of patients with ReA relied on cultures at the site of infection, serum antibodies, or both to confirm the diagnosis. There were inter/intra-group variations and overlapping of diagnostic criteria, at least 32 different terms referring to ReA or Reiter's syndrome, and 6 patterns of disease. According to these data, we propose 3 categories of disease for patients entering clinical and basic studies on ReA: probable ReA (2 subgroups); definite ReA triggered by bacteria (2 subgroups); and bacterial-associated undifferentiated oligoarthritis or spondyloarthropathy. CONCLUSION: This proposal provides a rationale for reducing the heterogeneity found in criteria for including patients with ReA in research and to facilitate scientific communication. In contrast to diagnostic criteria, this proposal does not restrict the study population to a minority of patients, but allows the investigator to include several forms of disease and to analyze results according to different categories.

Intradermal tophi in gout: a case-control study.

OBJECTIVE: To describe the characteristics of intradermal tophi in patients with gout and search for factors associated with their development. METHODS: This is a case-control study of patients with gout: cases (Group A, n = 21) had intradermal (not subcutaneous) plaques of monosodium urate (MSU) crystals located in sites distant to articular or paraarticular structures, and controls (Group B, n = 42) had gout but no intradermal tophi. Both Group A and Group B were paired by sex, age (+/-5 years), and duration of the disease (+/-3 years). Analysis included serum and urinary uric acid levels at first visit, radiographic stage of gout, the presence of associated diseases, and previous therapy, specifically, chronic glucocorticoid and diuretic usage. RESULTS: Intradermal tophi were located in the legs, forearms, buttocks, thighs, arms, and abdominal wall. Patients in Group A had a greater number of nonintradermal tophi in common sites (11.9+/-12.5 vs. 4.2+/-7.9, mean +/- SD; p = 0.018), decreased glomerular filtration rate (46.74+/-25.11 vs. 70.87+/-30.18 ml/min; p = 0.042), advanced radiographic changes (57.2 vs. 7.1%; p = 0.0001), and longterm glucocorticoid self-medication (76 vs. 36%; p = 0.006). We found no differences in other associated diseases between groups. CONCLUSION: Intradermal tophi were commonly found in the legs and forearms, and less frequently in the buttocks, thighs, and abdominal wall of gouty patients, and were associated with longterm self-prescribed glucocorticoids and chronic renal failure. The occurrence of intradermal tophi in these patients appeared to correlate with advanced disease.

Long-term exposure of adults to outdoor air pollution is associated with increased airway obstruction and higher prevalence of bronchial hyperresponsiveness.

The authors studied the association between long-term exposure (i.e., > 10 y) to outdoor air pollution and the severity of obstructive pulmonary disease and prevalence of bronchial hyperreactivity to beta2 agonists in two groups of adult patients who were of similar ages and who had similar smoking habits. The subjects lived in downtown districts or in the outer suburbs of Marseilles, the neighborhood that contained air samplers. The regions were similar with respect to sulfur dioxide levels, but levels of nitric oxides and particulate matter (10 millimeters or less) were higher in the downtown area than the suburbs. The authors assessed airway obstruction, as determined by a decrease in forced expiratory volume in 1 s, mean forced expiratory flow measured between 25% and 75% of vital capacity, and an elevated value of central airway resistance. The authors tested the changes in these variables induced by inhalation of a beta2 agonist. Baseline lung function was altered more significantly in both male and female patients who lived in downtown Marseilles than in those who resided in the suburbs, and the differences persisted regardless of the season during which the study occurred. Prevalence of bronchial hyperreactivity and symptoms of asthma (but not of rhinitis) were higher in the downtown than suburban male subjects. The results of this study suggest that an association exists between actual environmental exposure to outdoor air pollution (i.e., nitrogen oxides and/or particulate matter of 10 millimeters or less) and respiratory effects in sensitive adults represented by patients with chronic obstructive pulmonary disease or asthma.

Juvenile-onset spondyloarthropathies.

This article discusses the clinical spectrum and characteristics of juvenile-onset spondyloarthropathies and includes a review of the demographic, clinical, radiographic (and other imaging techniques), and laboratory data of conditions, syndromes, and diseases making up this group. The pathogenic role of several factors in the context of adult-onset patients, but also in regards to studies already performed in juvenile-onset patients, is discussed.