[Comparison of risk factors for hemorrhagic stroke and ischemic stroke, a prospective long-term follow-up cohort study].

Objective: To analyze and compare the risk factors for hemorrhagic stroke and ischemic stroke and understand the exposure levels in population. Methods: A cohort study of risk factors of stroke was conducted in a rural community in Fengxian District of Shanghai in 2003, and the common risk factors of stroke were investigated at baseline survey, the cerebrovascular hemodynamics indexes were detected, the cerebrovascular function score was calculated according to the unified integral rule, and the incidence of stroke was observed in follow up. The risk factors for hemorrhagic stroke and ischemic stroke were analyzed by cohort study. The risk factors for two subtypes of stroke were compared. Result: A total of 10 565 participants were included in the study, with a mean follow-up period of (11.15±2.26) years, and 103 hemorrhagic stroke cases and 268 ischemic stroke cases were observed during follow-up period. The independent risk factors of hemorrhagic stroke included decreased cerebrovascular function score [hazard ratio (HR)=1.56, 95%CI: 1.23-1.98], history of alcohol consumption (HR=2.46, 95%CI: 1.39-4.34), hypertension (HR=1.75, 95%CI: 1.00-3.07) and older age (HR=1.07, 95%CI: 1.04-1.10). The independent risk factors of ischemic stroke included decreased cerebrovascular function score (HR=1.43, 95%CI: 1.25-1.65), smoking history (HR=1.52, 95%CI: 1.13-2.05), hypertension (HR=1.51, 95%CI: 1.10-2.07), family history of stroke (HR=1.89, 95%CI: 1.13-3.15), left ventricular hypertrophy (HR=1.74, 95%CI: 1.07-2.81) and older age (HR=1.07, 95%CI: 1.05-1.08). Conclusions: Decreased cerebrovascular function score, hypertension, and older age were common independent risk factors of both types of stroke, alcohol consumption history was an independent risk factor of hemorrhagic stroke, and smoking history, and family history of stroke and left ventricular hypertrophy were independent risk factors of ischemic stroke.

Characteristics of flight delays during solar flares.

Solar flares are one of the severest solar activities that have important effects on near-Earth space. Previous studies have shown that flight arrival delays increase as a result of solar flares, but the intrinsic mechanism behind this relationship is still unknown. In this study, we conducted a comprehensive analysis of flight departure delays during 57 solar X-ray events by using a huge amount of flight data (~ 5 × 106 records) gathered over a 5-year period. It is found that the average flight departure delay time during solar X-ray events increased by 20.68% (7.67 min) compared to quiet periods. Our analysis also revealed apparent time and latitude dependencies, with flight delays being more serious on the dayside than on the nightside and longer (shorter) delays tending to occur in lower (higher) latitude airports during solar X-ray events. Furthermore, our results suggest that the intensity of solar flares (soft X-ray flux) and the Solar Zenith Angle directly modulate flight departure delay time and delay rate. These results indicate that communication interferences caused by solar flares directly affect flight departure delays. This work expands our conventional understanding of the impacts of solar flares on human society and provides new insights for preventing or coping with flight delays.

Additional flight delays and magnetospheric-ionospheric disturbances during solar storms.

Although the sun is really far away from us, some solar activities could still influence the performance and reliability of space-borne and ground-based technological systems on Earth. Those time-varying conditions in space caused by the sun are also called solar storm or space weather. It is known that aviation activities can be affected during solar storms, but the exact effects of space weather on aviation are still unclear. Especially how the flight delays, the top topic concerned by most people, will be affected by space weather has never been thoroughly researched. By analyzing huge amount of flight data (~ 4 × 106 records), for the first time, we quantitatively investigate the flight delays during space weather events. It is found that compared to the quiet periods, the average arrival delay time and 30-min delay rate during space weather events are significantly increased by 81.34% and 21.45% respectively. The evident negative correlation between the yearly flight regularity rate and the yearly mean total sunspot number during 22 years also confirms such correlation. Further studies show that the flight delay time and delay rate will monotonically increase with the geomagnetic field fluctuations and ionospheric disturbances. These results indicate that the interferences in communication and navigation during space weather events may be the most probable reason accounting for the increased flight delays. The above analyses expand the traditional field of space weather research and could also provide us with brand new views for improving the flight delay predications.

[A cross-sectional study on the clinical phenotypes of rheumatoid arthritis].

OBJECTIVE: To explore the characteristics and clinical phenotypes of rheumatoid arthritis (RA) and provide the basis for further understanding, interventions and outcomes of this disease. METHODS: RA patients attended at Peking University People's Hospital from 2018 to 2021 were enrolled in the study. Data collection included demographic data, the sites and numbers of joints involved, extra-articular manifestations (EAM), comorbidities and laboratory variables. Statistical and bioinformatical analysis was performed to establish clinical subtypes by clustering analysis based on the type of joint involved, EAM involvement and other autoimmune diseases overlapped. The characteristics of each subtype were analyzed. RESULTS: A total of 411 patients with RA were enrolled. The mean age was (48.84±15.17) years, and 346 (84.2%) were females. The patients were classified into 4 subtypes: small joint subtype (74, 18.0%), total joint subtype (154, 37.5%), systemic subtype (100, 24.3%), and overlapping subtype (83, 20.2%). The small joint subtype had no medium or large joint involvement, and 35.1% had systemic involvement. The erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) levels and platelet count (PLT) were lower than those in other subtypes, and the rates of positive rheumatoid factors (RF-IgA and RF-IgG) were significantly higher in the small joint subtype. The total joint subtype had both large and small joint involvement but no systemic involvement. The rate of morning stiffness and positive antinuclear antibodies (ANA) in this subtype were lower than those in other subtypes. In the systemic subtype, interstitial lung disease and secondary Sjögren syndrome were the most common systemic involvements, with prominent levels of disease activity score 28-joint count (DAS28-ESR and DAS28-CRP). The overlapping subtype was commonly combined with Hashimoto's thyroiditis or primary Sjögren syndrome. Female in the overlapping subtype was more common than in other subtypes. This subtype was characterized by hyperglobulinemia, hypocomplementemia and high rate of positive ANA, especially spotting type. CONCLUSION: Based on the clinical features, RA patients could be classified into 4 subtypes: small joint subtype, total joint subtype, systemic subtype, and overlapping subtype. Each subtype had its own clinical characteristics. They help for further understanding and a more individualized treatment strategy of RA.

[Association between mild cognitive impairment and all-cause mortality in elderly population in China: a Meta analysis].

Objective: To quantitatively evaluate the association between mild cognitive impairment and all-cause mortality. Methods: The research papers of the association between cognitive impairment and all-cause mortality in the elderly in the databases of PubMed, EMBASE, Wang Fang data and CNKI published as of August 1, 2021 were comprehensively retrieved. Software R 4.02 was used for Meta-analysis. Results: A total of 9 research papers were included, involving 48 709 patients. The quality of included papers was high. The results of Meta-analysis showed that the association between mild cognitive impairment and the increased risk of all-cause mortality was statistically significant. Compared with the normal cognitive population, the risk of mortality in the elderly with mild cognitive impairment increased by 39% (HR=1.39, 95%CI: 1.18-1.63). Conclusions: The current research evidence showed that mild cognitive impairment assessed by MMSE screening scale can be used as an independent predictor of the increased risk of all-cause mortality in the elderly population in China. However, due to the limitation of the number of included studies and sample size, the conclusions need to be supported by more evidence studies.

[Fitting and predicting trend of COVID-19 by SVEPIUHDR dynamic model].

Objective: To fit and predict the trend of COVID-19 epidemics in the United States (USA) and the United Kingdom (UK), and analyze the effect of vaccination. Methods: Based on the SEIR dynamic model, considering the presymptomatic infections, isolation measures, vaccine vaccination coverage, etc., we developed a SEIR with vaccine inoculation, Presymptomatic infectious, unconfirmed infectious, hospital isolation and domiciliary isolation dynamics model. The publicly released incidence data of COVID-19 from November 6, 2020 to January 31, 2021 in USA and from November 23, 2020 to January 31, 2021 in UK were used to fit the model and the publicly released incidence data of COVID-19 from February 1, 2021 to April 1 were used to evaluate the predicting power of the model by software R 4.0.3 and predict changes in the daily new cases in the context of different vaccination coverage. Results: According to the cumulative confirmed cases, the fitting bias and the predicting bias of the SVEPIUHDR model for USA and UK were less than 5%, respectively. From the model prediction results, the cumulative cases after COVID-19 vaccination in USA in early April reached 31 864 970. If there had not had such vaccination, the cumulative cases of COVID-19 would have reached to 35 317 082, with a gap of more than 3.4 million cases. In UK, the cumulative cases of COVID-19 after the vaccination was estimated to be 4 195 538 in early April, compared with 4 268 786 cases if no COVID-19 vaccination had been provided, there would have heen a gap of more than 70 000 cases. Conclusion: SVEPIUHDR model shows a good prediction effect on the epidemic of COVID-19 in both USA and UK.

[Family history of rheumatic diseases in patients with rheumatoid arthritis: a large scale cross-sectional study].

OBJECTIVE: To determine the associations between the family history of rheumatic diseases and clinical features in patients with rheumatoid arthritis (RA). METHODS: In total, eight hundred and ninety patients with RA were enrolled. The demographic and clinical data were collected, including gender, age, height, body weight, age of disease onset, history of smoking and drinking, family history of rheumatic diseases, clinical and laboratory features, pain and global visual analogue scale (VAS), and multi-dimensional health assessment questionnaire (MDHAQ). Finally, 803 patients were completed the dataset and were included in the study. RESULTS: In this cohort, the male/female ratio was 1:3.5, and the age of onset was (45.09±14.50) years. A total of 123 (15.32%) patients were accompanied with family history of rheumatic diseases, including RA, spondyloarthritis, Sjögren's syndrome, systemic lupus erythematosus and systemic sclerosis. The percentages of first degree, second degree and both first and second degree relatives were 91 (73.98%), 22 (17.89%), and 10 (8.13%) respectively. The most common disease was RA (70.73%), followed by other rheumatic diseases (21.95%), and RA combined with other rheumatic diseases (7.32%). The clinical and laboratory characteristics were compared between the patients with and without family history. The onset-age of the subjects was significantly different between those with and without family history of rheumatic diseases (39.97 ±13.68 vs. 46.01±14.46; P<0.01), which meant that the onset-age in patients with family history was 6.04 years earlier than that in patients without family history. The patients with family history had higher positive rate of rheumatoid factor (RF) compared with those without family history (78.48% vs. 66.67%, P<0.05). By adjusting with gender, body mass index (BMI), smoking and alcohol drinking, anti-cyclic citrullinated peptide (CCP) antibody and RF level, the age at disease onset in the patients with family history was 4.54 years earlier than that in the patients without family history (ß=-4.54; 95%CI:-8.70, -0.38; P<0.05). Further hierarchical regression analysis showed that, the age at onset of the RA patients with family history was 10.02 years earlier than that without family history among the smoking patients (ß= -10.02; 95%CI:-17.60, -2.43; P=0.01), while the age at onset of the RA patients with family history was 3.27 years earlier than that without family history among the never smoking patients (ß=-3.27; 95%CI:-8.37, 1.82; P=0.21). CONCLUSION: The family history of rheumatic diseases is a risk factor for early onset of RA, and may interact with smoking.

[Role of electrocardiogram in predicting cardiac resynchronization therapy response].

OBJECTIVE: To explore the role of electrocardiogram(ECG)in predicting cardiac resynchronization therapy (CRT) response. METHODS: This study retrospectively analyzed ECG of 92 CRT patients, who received CRT therapy from 2001 to 2013 in our center and were followed up for 6 months. The patients were divided into responder group (n=64) and non-responder group (n=28). The baseline and 6-month data including QRS width, heart rhythm and axis variation were analyzed. The definition of responder is left ventricular end systolic volume (LVESV) reduction ≥15% within 6 months after CRT. After CRT therapy, the ventricular activation was changed as left to right (frontal plane), posterior to anterior and axis changed in a clockwise direction. The change in more than two directions was defined as prominent axis change. Logistic analysis was performed to analyze the role of ECG in predicting CRT response. RESULTS: (1) Baseline parameter comparison between the two groups: the proportion of female and LBBB is significantly higher (P<0.01; P=0.04), while the proportion of atrial fibrillation/flutter (Af/AF) is significantly lower (P<0.01) in responder group than in non-responder group. The pre-CRT average QRS duration is much wider in responder group than in non-responder group (P=0.01). (2) Comparison of follow-up with baseline results in two groups: NYHA heart function level, 6 minutes walking distance, QRS duration, LVEF, LVESV improved significantly (P<0.01) post-CRT in responder group. In non-responder group, the QRS duration and LVESV deteriorated significantly (P=0.02, P<0.01), while post-CRT NYHA heart function level improved significantly. In responder group, pre-CRT ECG axis of 53 patients (82.8%) pointed to left and 58 patients (90.6%) pointed to posterior; post-CRT ECG axis of 49 patients (76.6%) pointed to right and 30 patients (40.6%) pointed to anterior. In non-responder group, pre-CRT ECG axis of 25 patients (89.3%) pointed to left and 24 patients (85.7%) pointed to posterior; post-CRT ECG axis of 17 patients (60.7%) pointed to right and 12 patients (42.9%) pointed to anterior. Post-CRT, the proportion of ECG axis prominent change was significantly higher in responder than in non-responder group (62.5%(40/64) vs. 32.1%(9/28), P=0.007). (3)Predicting value: pre-CRT QRS width ≥140 ms (OR=4.97, 95% CI 1.53 to 16.13, P=0.008)and post-CRT prominent axis change (OR=5.1, 95% CI 1.67 to 15.5, P=0.004)were found to be independent predictors of CRT responders. Af/AF pre-CRT was associated with reduced CRT response (OR=0.25, 95% CI 0.08 to 0.80, P=0.02). CONCLUSIONS: ECG may play a role in predicting CRT response. QRS width and Af/AF before CRT and ECG axis change post-CRT could be used to predict CRT response.

Association between PADI4 gene polymorphisms and anti-cyclic citrullinated peptide antibody positive rheumatoid arthritis in a large Chinese Han cohort.

OBJECTIVES: The present study was undertaken to investigate the association of peptidyl-arginine-deiminase type IV gene (PADI4) single nucleotide polymorphisms (SNPs) with rheumatoid arthritis (RA) susceptibility, and to determine whether there is any impact of PADI4 polymorphisms on RA subsets or phenotypes in a large Chinese Han cohort. METHODS: Two PADI4 SNPs (rs2240340 and rs1748033) were genotyped in 1216 Chinese Han RA patients and 1040 unaffected controls by TaqMan SNP Assays. Serum anti-CCP antibody and anti-PAD4 antibody levels were measured by ELISA. Bone destruction was scored by Sharp-van der Heijde scores (SHSs) of hands in 463 patients. RESULTS: The two SNPs rs2240340 and rs1748033 of PADI4 showed strong association with RA susceptibility (OR=1.23, 95% CI 1.09-1.38, p=6.66×10⁻4; and OR=1.24, 95% CI 1.10-1.41, p=6.98×10⁻4, respectively). RA risk genotypes of PADI4 were specifically associated with anti-CCP positive RA (rs2240340: p=5.13×10⁻6; rs1748033: p=2.97×10⁻³, respectively). Furthermore, there was a trend association between PADI4 rs2240340 and radiographic severity, though it did not reach the statistic significance (p=0.088). CONCLUSIONS: Our data provide strong evidence that PADI4 polymorphisms are risk factors contributed to RA susceptibility, especially for anti-CCP positive RA, and may confer higher risk of RA radiographic severity in Chinese Han population.

Aurora-A is a determinant of tamoxifen sensitivity through phosphorylation of ERα in breast cancer.

Despite the clinical success of tamoxifen, its resistance remains a major challenge in breast cancer. Here we show that Aurora-A determines tamoxifen sensitivity by regulation of oestrogen receptor (ER)α. Ectopic expression of Aurora-A decreases and depletion of Aurora-A enhances tamoxifen sensitivity in ERα-positive breast cancer. Elevated Aurora-A was significantly associated with the recurrence of ERα-positive tumours. Notably, Aurora-A inhibitor MLN8237, which is currently in clinical trial, synergizes with tamoxifen and overcomes tamoxifen resistance. Furthermore, Aurora-A interacts with and phosphorylates ERα on serine-167 and -305, leading to increase in ERα DNA-binding and transcriptional activity. Elevated levels of Aurora-A are significantly associated with disease-free survival in ERα-positive but not ERα-negative breast cancers. These data suggest that Aurora-A has a pivotal role in tamoxifen resistance and ERα is a bona fide substrate of Aurora-A. Thus, Aurora-A represents a prognostic marker in ERα-positive tumour and a critical therapeutic target in tamoxifen-resistant breast cancer, and Aurora-A inhibitor could be used as either an independent or concurrent agent in tamoxifen-resistant tumour.

Population pharmacokinetics of valnemulin in swine.

This study was carried out in 121 pigs to develop a population pharmacokinetic (PPK) model by oral (p.o.) administration of valnemulin at a single dose of 10 mg/kg. Serum biochemistry parameters of each pig were determined prior to drug administration. Three to five blood samples were collected at random time points, but uniformly distributed in the absorption, distribution, and elimination phases of drug disposition. Plasma concentrations of valnemulin were determined by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The concentration-time data were fitted to PPK models using nonlinear mixed effect modeling (NONMEM) with G77 FORTRAN compiler. NONMEM runs were executed using Wings for NONMEM. Fixed effects of weight, age, sex as well as biochemistry parameters, which may influence the PK of valnemulin, were investigated. The drug concentration-time data were adequately described by a one-compartmental model with first-order absorption. A random effect model of valnemulin revealed a pattern of log-normal distribution, and it satisfactorily characterized the observed interindividual variability. The distribution of random residual errors, however, suggested an additive model for the initial phase (<12 h) followed by a combined model that consists of both proportional and additive features (≥ 12 h), so that the intra-individual variability could be sufficiently characterized. Covariate analysis indicated that body weight had a conspicuous effect on valnemulin clearance (CL/F). The featured population PK values of Ka , V/F and CL/F were 0.292/h, 63.0 L and 41.3 L/h, respectively.

Population pharmacokinetics of cefquinome in pigs.

This study was performed in 145 pigs to develop a population pharmacokinetics (PPK) model by i.m. administration of cefquinome (CEQ) at the dose of 2 mg/kg in the neck muscle. Serum physiological and biochemical parameters for each pig were determined before administration. After administration, 2-4 samples were collected at random, with the sampling point evenly distributed in the three periods (<1 h, 1-4 h and >4 h). The plasma concentration of CEQ was determined by high performance liquid chromatography with UV detector. The pharmacostatistical analyses of concentration-time data, weight, age, gender, serum physiological and biochemical parameters were performed with nonlinear mixed effect modeling (NONMEM). A one-compartmental model with first-order absorption and elimination adequately described the data from the study group. The optimal random effect model of pharmacokinetics parameters was of log-normal distribution and the residual errors assumed a mixed-type model (proportional and additive) to best explain intra-individual variability. Covariate analysis showed that body weight is positively correlated with apparent volume of distribution (V/F) and body clearance (CL/F). The typical PPK parameters of Ka , CL, and V were 0.564/h, 5.15 L/h, and 1.36 L, respectively.

An evaluation of resident exposure to respirable particulate matter and health economic loss in Beijing during Beijing 2008 Olympic Games.

Previous epidemiological studies showed that air pollutants, especially respirable particulate matter, including PM(10), could impose harmful effects on human health. The assessment of the effects of PM(10) on mortality and morbidity makes an important basis for enhancing pollution control efforts, and for protecting public health. In this study, we measured the levels of Beijing residents' exposure to PM(10) during three different time periods around the Beijing Olympic Games held in 2008, and calculated the economic cost associated with human health. A comparative analysis of human exposure to PM(10) and associated health economics was also made to see the difference between 2005 and 2008. GIS technology was employed to interpolate the distribution of population and PM(10) data collected by 27 stations at a scale of 1kmx1km. Study results show that Beijing's population is distributed in a highly inhomogeneous manner, with the majority of people dwelling in the city proper. During the Olympic Games, population-weighted PM(10) exposure came down by 46% and 19% respectively, compared with the pre-OG and the post-OG periods. Consequently, the economic cost associated with human health during the Games came down by 38% and 16% respectively, compared with the pre-OG and the post-OG periods. Comparative analysis shows that during the Olympic Games, both PM(10) and the economic cost associated with health as a proportion of GDP sat at the bottom of the 4-year statistics, indicating that in addition to favorable weather conditions, enhanced traffic and emission control policies and measures have produced a noticeable effect on PM(10) reduction.

RGMA and IL21R show association with experimental inflammation and multiple sclerosis.

Rat chromosome 1 harbors overlapping quantitative trait loci (QTL) for cytokine production and experimental models of inflammatory diseases. We fine-dissected this region that regulated cytokine production, myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), anti-MOG antibodies and pristane-induced arthritis (PIA) in advanced intercross lines (AILs). Analysis in the tenth and twelfth generation of AILs resolved the region in two narrow QTL, Eae30 and Eae31. Eae30 showed linkage to MOG-EAE, anti-MOG antibodies and levels of interleukin-6 (IL-6). Eae31 showed linkage to EAE, PIA, anti-MOG antibodies and levels of tumor necrosis factor (TNF) and IL-6. Confidence intervals defined a limited set of potential candidate genes, with the most interesting being RGMA, IL21R and IL4R. We tested the association with multiple sclerosis (MS) in a Nordic case-control material. A single nucleotide polymorphism in RGMA associated with MS in males (odds ratio (OR)=1.33). Polymorphisms of RGMA also correlated with changes in the expression of interferon-gamma (IFN-gamma) and TNF in cerebrospinal fluid of MS patients. In IL21R, there was one positively associated (OR=1.14) and two protective (OR=0.87 and 0.68) haplotypes. One of the protective haplotypes correlated to lower IFN-gamma expression in peripheral blood mononuclear cells of MS patients. We conclude that RGMA and IL21R and their pathways are crucial in MS pathogenesis and warrant further studies as potential biomarkers and therapeutic targets.

Wavefront reconstruction and three-dimensional shape measurement by two-step dc-term-suppressed phase-shifted intensities.

A wavefront reconstruction and three-dimensional (3-D) shape measurement method by a two-step phase-shifting algorithm with arbitrary phase shift in (0,pi) is proposed. In this method, only two phase-shifted intensities, with the removal of the dc term by an averaging technique in spatial domain or low-pass filter operation in the frequency domain, are needed, and the other additional measurements are no longer required. The simulation for an irregular wavefront has shown the feasibility, and the optical experiment for a 3-D face mask in the case of a sinusoidal fringe projection system has illustrated the validity of the proposed method.

The rat antigen-presenting lectin-like receptor complex influences innate immunity and development of infectious diseases.

Genetic variation in the antigen-presenting lectin-like receptor gene complex (APLEC) associates with autoimmunity and arthritis in rats and humans. We hypothesized that the encoded C-type lectin-like receptors might influence innate immunity and responses to infectious agents. To test this hypothesis, we compared in vivo and in vitro phenotypes in DA rats and APLEC-congenic rats. Survival rates following infection with Staphylococcus aureus and Herpes simplex virus differed significantly between the two strains. Likewise, differential delayed type hypersensitivity (DTH), an immunological reaction involving T lymphocytes and macrophages, was observed in response to provocation with the chemical oxazolone. Unstimulated bone marrow-derived macrophages from the two strains appeared to already have polarized activation states with different mRNA levels of CD163 and Dectin-1 receptors. Following stimulation with a panel of microbial agents, differences in induced mRNA and protein levels were shown for interleukin (IL)-6 and IL-10 following stimulation with lipopolysaccharide, mannan and beta-glucan. Expression levels of APLEC gene mRNAs also differed, and both strains had a notably dichotomous expression of the genes, with general downregulation of all four Dcir genes and upregulation of Mincle and Mcl. We suggest that human APLEC genes may similarly regulate infectious diseases, DTH and general macrophage activation status.

Definition of arthritis candidate risk genes by combining rat linkage-mapping results with human case-control association data.

OBJECTIVE: To define genomic regions that link to rat arthritis and to determine the potential association with rheumatoid arthritis (RA) of the corresponding human genomic regions. METHODS: Advanced intercross lines (AIL) between arthritis susceptible DA rats and arthritis resistant PVG.1AV1 rats were injected with differently arthritogenic oils to achieve an experimental situation with substantial phenotypic variation in the rat study population. Genotyping of microsatellite markers was performed over genomic regions with documented impact on arthritis, located on rat chromosomes 4, 10 and 12. Linkage between genotypes and phenotypes were determined by R/quantitative trait loci (QTL). Potential association with RA of single nucleotide polymorphisms (SNPs) in homologous human chromosome regions was evaluated from public Wellcome Trust Case Control Consortium (WTCCC) data derived from 2000 cases and 3000 controls. RESULTS: A high frequency of arthritis (57%) was recorded in 422 rats injected with pristane. Maximum linkage to pristane-induced arthritis occurred less than 130 kb from the known genetic arthritis determinants Ncf1 and APLEC, demonstrating remarkable mapping precision. Five novel quantitative trait loci were mapped on rat chromosomes 4 and 10, with narrow confidence intervals. Some exerted sex-biased effects and some were linked to chronic arthritis. Human homologous genomic regions contain loci where multiple nearby SNPs associate nominally with RA (eg, at the genes encoding protein kinase Calpha and interleukin 17 receptor alpha). CONCLUSIONS: High-resolution mapping in AIL populations defines limited sets of candidate risk genes, some of which appear also to associate with RA and thus may give clues to evolutionarily conserved pathways that lead to arthritis.

Accessibility of a critical prion protein region involved in strain recognition and its implications for the early detection of prions.

Human prion diseases are characterized by the accumulation in the brain of proteinase K (PK)-resistant prion protein designated PrP27 - 30 detectable by the 3F4 antibody against human PrP109 - 112. We recently identified a new PK-resistant PrP species, designated PrP*20, in uninfected human and animal brains. It was preferentially detected with the 1E4 antibody against human PrP 97 - 108 but not with the anti-PrP 3F4 antibody, although the 3F4 epitope is adjacent to the 1E4 epitope in the PrP*20 molecule. The present study reveals that removal of the N-terminal amino acids up to residue 91 significantly increases accessibility of the 1E4 antibody to PrP of brains and cultured cells. In contrast to cells expressing wild-type PrP, cells expressing pathogenic mutant PrP accumulate not only PrP*20 but also a small amount of 3F4-detected PK-resistant PrP27 - 30. Remarkably, during the course of human prion disease, a transition from an increase in 1E4-detected PrP*20 to the occurrence of the 3F4-detected PrP27 - 30 was observed. Our study suggests that an increase in the level of PrP*20 characterizes the early stages of prion diseases.