Gene ontology: tool for the unification of biology. The Gene Ontology Consortium

Genomic sequencing has made it clear that a large fraction of the genes specifying the core biological functions are shared by all eukaryotes. Knowledge of the biological role of such shared proteins in one organism can often be transferred to other organisms. The goal of the Gene Ontology Consortium is to produce a dynamic, controlled vocabulary that can be applied to all eukaryotes even as knowledge of gene and protein roles in cells is accumulating and changing. To this end, three independent ontologies accessible on the World-Wide Web (http://www.geneontology.org ) are being constructed: biological process, molecular function and cellular component.

The Gene Ontology (GO) database and informatics resource

The Gene Ontology (GO) project (http://www. geneontology.org/) provides structured, controlled vocabularies and classifications that cover several domains of molecular and cellular biology and are freely available for community use in the annotation of genes, gene products and sequences. Many model organism databases and genome annotation groups use the GO and contribute their annotation sets to the GO resource. The GO database integrates the vocabularies and contributed annotations and provides full access to this information in several formats. Members of the GO Consortium continually work collectively, involving outside experts as needed, to expand and update the GO vocabularies. The GO Web resource also provides access to extensive documentation about the GO project and links to applications that use GO data for functional analyses.

Comparative genomics of the eukaryotes

A comparative analysis of the genomes of Drosophila melanogaster, Caenorhabditis elegans, and Saccharomyces cerevisiae-and the proteins they are predicted to encode-was undertaken in the context of cellular, developmental, and evolutionary processes. The nonredundant protein sets of flies and worms are similar in size and are only twice that of yeast, but different gene families are expanded in each genome, and the multidomain proteins and signaling pathways of the fly and worm are far more complex than those of yeast. The fly has orthologs to 177 of the 289 human disease genes examined and provides the foundation for rapid analysis of some of the basic processes involved in human disease.

Reactome: a knowledgebase of biological pathways

Reactome, located at http://www.reactome.org is a curated, peer-reviewed resource of human biological processes. Given the genetic makeup of an organism, the complete set of possible reactions constitutes its reactome. The basic unit of the Reactome database is a reaction; reactions are then grouped into causal chains to form pathways. The Reactome data model allows us to represent many diverse processes in the human system, including the pathways of intermediary metabolism, regulatory pathways, and signal transduction, and high-level processes, such as the cell cycle. Reactome provides a qualitative framework, on which quantitative data can be superimposed. Tools have been developed to facilitate custom data entry and annotation by expert biologists, and to allow visualization and exploration of the finished dataset as an interactive process map. Although our primary curational domain is pathways from Homo sapiens, we regularly create electronic projections of human pathways onto other organisms via putative orthologs, thus making Reactome relevant to model organism research communities. The database is publicly available under open source terms, which allows both its content and its software infrastructure to be freely used and redistributed.

Inhibition of Bax channel-forming activity by Bcl-2

Proteins of the Bcl-2 family are intracellular membrane-associated proteins that regulate programmed cell death (apoptosis) either positively or negatively by as yet unknown mechanisms. Bax, a pro-apoptotic member of the Bcl-2 family, was shown to form channels in lipid membranes. Bax triggered the release of liposome-encapsulated carboxyfluorescein at both neutral and acidic pH. At physiological pH, release could be blocked by Bcl-2. Bcl-2, in contrast, triggered carboxyfluorescein release at acidic pH only. In planar lipid bilayers, Bax formed pH- and voltage-dependent ion-conducting channels. Thus, the pro-apoptotic effects of Bax may be elicited through an intrinsic pore-forming activity that can be antagonized by Bcl-2.

Growth curves and survival characteristics of the animals used in the Biomarkers of Aging Program

The collaborative Interagency Agreement between the National Center for Toxicological Research (NCTR) and the National Institute on Aging (NIA) was aimed at identifying and validating a panel of biomarkers of aging in rodents in order to rapidly test the efficacy and safety of interventions designed to slow aging. Another aim was to provide a basis for developing biomarkers of aging in humans, using the assumption that biomarkers that were useful across different genotypes and species were sensitive to fundamental processes that would extrapolate to humans. Caloric restriction (CR), the only intervention that consistently extends both mean and maximal life span in a variety of species, was used to provide a model with extended life span. C57BI/6NNia, DBA/2JNia, B6D2F1, and B6C3F1 mice and Brown Norway (BN/RijNia), Fischer (F344/NNia) and Fischer x Brown Norway hybrid (F344 x BN F1) rats were bred and maintained on study. NCTR generated data from over 60,000 individually housed animals of the seven different genotypes and both sexes, approximately half ad libitum (AL) fed, the remainder CR. Approximately half the animals were shipped to offsite NIA investigators internationally, with the majority of the remainder maintained at NCTR until they died. The collaboration supplied a choice of healthy, long-lived rodent models to investigators, while allowing for the development of some of the most definitive information on life span, food consumption, and growth characteristics in these genotypes under diverse feeding paradigms.

Functional annotation of a full-length mouse cDNA collection

The RIKEN Mouse Gene Encyclopaedia Project, a systematic approach to determining the full coding potential of the mouse genome, involves collection and sequencing of full-length complementary DNAs and physical mapping of the corresponding genes to the mouse genome. We organized an international functional annotation meeting (FANTOM) to annotate the first 21,076 cDNAs to be analysed in this project. Here we describe the first RIKEN clone collection, which is one of the largest described for any organism. Analysis of these cDNAs extends known gene families and identifies new ones.

Lung cancer and cryptogenic fibrosing alveolitis. A population-based cohort study

Cryptogenic fibrosing alveolitis has been reported to be associated with an increased risk of lung cancer. However, it has recently become apparent that cigarette smoking may be a risk factor for cryptogenic fibrosing alveolitis as well as for lung cancer, and so may confound the association between these conditions. We have therefore estimated the independent increase in lung cancer incidence in patients with cryptogenic fibrosing alveolitis compared with the general population in a population-based cohort study involving 890 subjects with cryptogenic fibrosing alveolitis and 5, 884 control subjects drawn from the United Kingdom General Practice Research Database. The incidence of lung cancer was markedly increased among patients with cryptogenic fibrosing alveolitis (rate ratio [RR] 7.31, 95% confidence interval [95% CI] 4.47 to 11.93, p < 0.001), and adjustment for previous smoking history had little effect on this odds ratio (adjusted RR: 8.25, 95% CI 4.70 to 11.48, p < 0.001). This increase in lung cancer incidence remained when the analysis was restricted to current smokers (RR 7.36, 95% CI 1.54 to 35.19, p = 0.012). This study provides clear evidence that the incidence of lung cancer is increased in patients with cryptogenic fibrosing alveolitis, and that this effect is independent of the effect of cigarette smoking.

Organization and reorganization of immunoglobulin genes in A-MULV-transformed cells: rearrangement of heavy but not light chain genes

The structure of immunoglobulin-related gene was analyzed in individual Abelson murine leukemia virus (A-MuLV)-transformed lymphoid cell lines. Essentially all of these lines, whether immunoglobulin-containing or null, had DNA rearrangements in the vicinity of the JH regions on both chromosomes as well as deletions of at least 5 kb of DNA 5' to JH. None of these lines, however, except rare light chain producers, had detectable rearrangement at either their kappa or lambda light chain loci. In contrast to A-MuLV-transformants derived from bone marrow. Those from early fetal liver frequently contained more than two and sometimes 12 or more distinct, rearranged JH-containing fragments. Cellular subclones derived from these lines had a subset, usually two, of the fragments found in the parent line. Therefore, heavy chain gene rearrangement appears to precede that of light chain gene rearrangement and is still continuing in certain cultured A-MuLV transformants.

The defect in murine severe combined immune deficiency: joining of signal sequences but not coding segments in V(D)J recombination

Pre-B and pre-T cell lines from mutant mice with severe combined immune deficiency (scid mice) were transfected with plasmids that contained recombination signal sequences of antigen receptor gene elements (V, D, and J). Recovered plasmids were tested for possible recombination of signal sequences and/or the adjacent (coding) sequences. Signal ends were joined, but recombination was abnormal in that half of the recombinants had lost nucleotides from one or both signals. Coding ends were not joined at all in either deletional or inversional V(D)J recombination reactions. However, coding ends were able to participate in alternative reactions. The failure of coding joint formation in scid pre-B and pre-T cells appears sufficient to explain the absence of immunoglobulin or T cell receptor production in scid mice.

Seroprevalence, correlates, and characteristics of undetected coeliac disease in England

OBJECTIVE

To examine the seroprevalence, correlates, and characteristics of undetected coeliac disease in a large adult population sample in Cambridge, UK.

METHODS

The Cambridge General Practice Health Study invited individuals from 12 general practices, aged 45-76 years, to attend for a health survey that included a bone density measurement, between 1990 and 1995. A total of 7550 participants' serum samples were tested for antiendomysial antibody (EMA). Seroprevalence of undetected coeliac disease was based on EMA positivity. Differences between EMA positive and negative participants of various physiological correlates and reported characteristics were estimated by multivariate logistic and linear regression and adjusted for age, sex, social class, and smoking behaviour.

RESULTS

The seroprevalence of undetected coeliac disease in this general population sample aged 45-76 was 1.2% (95% confidence interval (CI) 0.9-1.4). EMA positive participants (n=87) were on average slightly lighter by 2.2 kg (p=0.08), were more likely to have reported their general health as being "good or excellent" (odds ratio (OR) 1.76 (95% CI 0.90-3.46)), and were less likely to report being a current smoker (OR for current versus never 0.36 (95% CI 0.14-0.90)) than EMA negative participants. EMA positivity was associated with an 8% reduction in mean serum cholesterol (0.5 mmol/l; p<0.01) and reductions in mean haemoglobin (0.3 g/dl; p<0.01), total protein (1.0 g/l; p<0.05), and corrected serum calcium (0.02 mmol/l; p<0.05). There was an increased risk of osteoporosis in EMA positive participants (OR 3.1 (95% CI 1.3-7.2)) and of mild anaemia (OR 4.6 (95% CI 2.5-8.2)) compared with EMA negative participants.

CONCLUSIONS

Undetected coeliac disease is likely to affect approximately 1% of the population of England aged 45-76 years, a value similar to several other countries. Those affected report "better health" but they do have an increased risk of osteoporosis and mild anaemia. In contrast, they have a favourable cardiovascular risk profile that may afford protection from ischaemic heart disease and stroke.

Doctor-patient interactions in oncology

Studies which apply content analysis techniques to the cancer consultation are few. This descriptive study examines the structure and content of the bad news cancer consultations of 117 outpatients newly referred to the Medical Oncology Department of a large London teaching hospital. From previous communication research three main hypotheses are formed: (i) the cancer consultation is clinician-dominated rather than patient-centred; (ii) the level of psychosocial discussion between clinicians and patients is low and (iii) patient characteristics such as sex, age and prognostic category influence clinician behaviours. Each patient had two consultations with one of 5 oncologists. Both these were audiotaped with the patients' consent. The tapes were content coded using the Roter Interaction Analysis System. Results showed that clinicians tended to use closed rather than open questions. Patients asked few questions and were seldom given space to initiate discussion. Thus, the level of patient-centredness was low. Despite the fact that consultations concerned life threatening disease and often contained information regarding toxic treatment which is known to provoke psychological dysfunction, the number of questions relating to patients' psychological health were few. The amount of discussion concerning medical topics from both parties was 2.5 times greater than the amount of psychosocial discussion. Although there was a suggestion in the data that 3 clinicians showed variations in behaviour according to patient age and prognostic group, the number of patients for each doctor was small. Patients were well informed about their diagnosis, prognosis and treatment options, but their emotional well-being was rarely probed.

Evidence of intra-specific competition for food in a pelagic seabird

The factors affecting the population dynamics of seabirds have long intrigued biologists. Current data suggest that density-dependent depletion of prey during the breeding season may regulate population size. However, much of the evidence for this has been circumstantial, and the underlying mechanisms are unclear. Here, we show that the per capita population growth rates of northern gannet Morus bassanus at colonies in Britain and Ireland have declined with increasing population size. Furthermore, direct observations reveal that the mean foraging trip duration of breeding gannets is positively correlated with colony size, both among colonies of different sizes in the same year, and within colonies as they change in size. To understand this phenomenon, we have developed a model which demonstrates that disturbance of fish alone can readily generate conditions under which gannets at larger colonies have to travel further to obtain food.

The distribution of plasma lipoproteins in middle-aged male runners

Stimulated by increasing evidence of an inverse relationship between plasma high-density lipoprotein cholesterol level and frequency of coronary heart disease, we determined concentrations of fasting plasma cholesterol, triglyceride, and lipoproteins in 41 very active men (running greater than 15 miles/wk for the previous year) 35-59 years of age (mean age, 47) and in a comparison group of men of similar age, randomly selected from three northern California communities. The runners had significantly (p less than 0.05) decreased mean plasma triglyceride (70 versus 146 mg/100 ml), total plasma cholesterol (200 versus 210 mg/100 ml), and low-density lipoprotein (LDL) cholesterol (125 versus 139 mg/100 ml) concentrations, and a higher mean level of high-density lipoprotein (HDL) cholesterol (64 versus 43 mg/100 ml) than the comparison group (n equals 147 for HDL and LDL; n equals 743 for total cholesterol and triglycerides). These very active men exhibited a plasma lipoprotein profile resembling that of younger women rather tan of sedentary, middle-aged men. This characteristic, and apparently advantageous, pattern could be only partially accounted for by differences in adiposity between runners and control subjects.

Prevalence of wheeze and asthma and relation to atopy in urban and rural Ethiopia

BACKGROUND

Asthma and allergy in developing countries may be associated with adoption of an urbanised "western" lifestyle. We compared the rates of asthma symptoms and atopy in urban populations in Jimma, southwest Ethiopia, at an early stage of economic development with those among the population of remote, rural, subsistence areas, and assessed the potential role of environmental aetiological factors leading to the differences.

METHODS

Information on wheeze of 12 months' duration, diagnosed asthma, and cough for 3 months of the year was gathered by questionnaire in random household samples of 9844 people from urban Jimma and of 3032 from rural areas. Atopy was defined by allergen skin-test response to Dermatophagoides pteronyssinus and mixed threshings measured in a one-in-four subsample of those aged 5 years and older from both groups.

FINDINGS

All respiratory symptoms were rare in children and were significantly less common overall in the rural than in urban group (wheeze odds ratio 0.31 [95% CI 0.22-0.43], p < 0.0001). Asthma was reported by 351 (3.6%) of the urban group, with a median reported duration of 8.5 years (IQR 4-17 years) that was unrelated to age. Atopy was a strong risk factor for asthma in urban Jimma. In the rural areas, skin sensitivity to mixed threshings was only slightly less common than in urban Jimma (0.67 [0.40-1.12], p = 0.13), whereas sensitivity to D pteronyssinus was significantly more common (3.24 [2.40-4.38], p < 0.0001), and since none of the 119 atopic individuals in the rural area reported wheeze or asthma, atopy was possibly associated with a reduction in the risk of disease among this group. Wheeze or D pteronyssinus sensitivity were positively associated with housing style, bedding materials, and use of malathion insecticide, but no single factor accounted for the urban-rural differences.

INTERPRETATION

Wheeze and asthma are especially rare in rural subsistence areas, and atopy may be associated with a reduced prevalence of these symptoms in this environment. In urban Jimma, self-reported asthma seemed to emerge as a clinical problem about 10 years before our study began, which is consistent with an effect of new environmental exposures. The factor or factors leading to the increase in asthma and allergy have not been identified, although exposures related to general changes in the domestic environment are likely to be involved.

Continuing kappa-gene rearrangement in a cell line transformed by Abelson murine leukemia virus

A cell line transformed by Abelson murine leukemia virus, called PD, is capable of carrying out kappa-gene rearrangement while growing in culture. Subclones of PD have diverse kappa-gene structures, and some derivatives show evidence of continued joining activity after as many as three subclonings. Analysis of PD sublineages has shown that a rearranged chromosome can undergo secondary kappa-gene rearrangements, producing either a new rearrangement or a deletion of C kappa. Although the PD line actively rearranges its kappa genes, its rearranged heavy-chain genes show little variation, and there is no rearrangement of lambda genes. In PD subclones, DNA fragments representing the reciprocal product of kappa-gene rearrangement are often evident, and they may undergo either further rearrangement or deletion. The implications of multiple rearrangements on a single chromosome and of the maintenance of reciprocal fragments are considered in the context of a model that postulates that the V kappa and J kappa segments are not all organized in the DNA in the same transcriptional direction, leading to inversions rather than deletions during joining.

Randomised controlled trial of cognitive-behavioural therapy in early schizophrenia: acute-phase outcomes

BACKGROUND

Cognitive-behavioural therapy (CBT) improves persistent psychotic symptoms.

AIMS

To test the effectiveness of added CBT in accelerating remission from acute psychotic symptoms in early schizophrenia.

METHOD

A 5-week CBT programme plus routine care was compared with supportive counselling plus routine care and routine care alone in a multi-centre trial randomising 315 people with DSM-IV schizophrenia and related disorders in their first (83%) or second acute admission. Outcome assessments were blinded.

RESULTS

Linear regression over 70 days showed predicted trends towards faster improvement in the CBT group. Uncorrected univariate comparisons showed significant benefits at 4 but not 6 weeks for CBT v. routine care alone on Positive and Negative Syndrome Scale total and positive sub-scale scores and delusion score and benefits v. supportive counselling for auditory hallucinations score.

CONCLUSIONS

CBT shows transient advantages over routine care alone or supportive counselling in speeding remission from acute symptoms in early schizophrenia.

Relation between cognitive and motor-oriented systems of visual position perception

Although subjects failed to detect a target displacement if it occurred near the time of a saccadic eye movement (a cognitive visual task), they were still able to point to the center of the target with an unseen pointer (a motor visual task). Pointing performance was not affected by detecting or failing to detect a stimulus displacement. The experiments demonstrate that some information that is available to a motor-oriented visual system is unavailable to the cognitive visual system, under conditions simulating normal perception.

Hippocampal volumes in cognitively normal persons at genetic risk for Alzheimer's disease

Brain imaging techniques have the potential to characterize neurobiological changes that precede the onset of cognitive impairment in persons at risk for Alzheimer's disease. As previously described, positron emission tomography (PET) was used to compare 11 cognitively normal persons 50 to 62 years of age who were homozygous for the epsilon4 allele of apolipoprotein E and 22 persons without the epsilon4 allele with a reported family history of Alzheimer's dementia who were matched for sex, age, and level of education. The epsilon4 homozygotes had significantly reduced glucose metabolism in the same brain regions as patients with Alzheimer's dementia; the largest reduction was in the posterior cingulate cortex. As described here, magnetic resonance imaging (MRI) was used to compare hippocampal volumes in the same subject groups. The epsilon4 homozygotes showed nonsignificant trends for smaller left and right hippocampal volumes; overall, smaller hippocampal volumes were associated with reduced performance on a long-term memory test. Whereas PET measurements of cerebral glucose metabolism begin to decrease before the onset of memory decline, MRI measurements of hippocampal volume begin to decrease in conjunction with memory decline in cognitively normal persons at risk for Alzheimer's disease.

Occupational exposure to metal or wood dust and aetiology of cryptogenic fibrosing alveolitis

BACKGROUND

We have previously suggested that cryptogenic fibrosing alveolitis (CFA) may be caused by occupational exposures, particularly to metal or wood dust. We have specifically investigated this hypothesis in a case-control study of patients with CFA.

METHODS

We obtained lifetime occupational histories by postal questionnaire from 218 patients with CFA and 569 controls matched for age, sex, and community, living in the Trent region of the UK. Information was subsequently verified by telephone interview in 165 cases and 408 controls. Serum IgE, rheumatoid factor, and antinuclear antibodies and skin sensitivity to common allergens were measured in cases and in one matched control for each.

FINDINGS

The relative risk of CFA, after adjustment for smoking, was significantly increased in relation to questionnaire-reported exposure to metal dust (odds ratio 1.68 [95% CI 1.07-2.65], p = 0.024) or to wood dust (1.71 [1.01-2.92], p = 0.048). Similar results were obtained with the telephone interview data. Significant exposure-response effects were found for both metal-dust and wood-dust exposure. CFA was also associated with the presence of rheumatoid factor or antinuclear antibodies, but not with positive allergen skin tests or raised IgE concentrations. There was no evidence of interaction between the effects of rheumatoid factor, antinuclear antibodies, positive skin allergen tests, or IgE concentrations and exposure to metal or wood dust. The combined aetiological fraction attributable to exposure to metal or wood dust was of the order of 20%.

INTERPRETATION

Occupational exposures to metal or wood dust are independent risk factors for CFA. Avoidance or limitation of these exposures may provide an opportunity to prevent the disease.

The role of the iminosugar N-butyldeoxynojirimycin (miglustat) in the management of type I (non-neuronopathic) Gaucher disease: a position statement

N-Butyldeoxynojirimycin (NB-DNJ, miglustat 'Zavesca') is an orally active iminosugar which inhibits the biosynthesis of macromolecular substrates that accumulate pathologically in glycosphingolipidoses. Clinical trials of NB-DNJ in patients with Gaucher's disease demonstrate the therapeutic potential of such substrate inhibitors in the glycolipid storage disorders. However, macrophage-targetted enzyme replacement using intravenous mannose-terminated human glucocerebrosidase (imiglucerase, Cerezyme) is highly effective in ameliorating many of the manifestations of Gaucher's disease and is a treatment in widespread use. Given that imiglucerase and miglustat are now both licensed for the treatment of Gaucher's disease, there is a need to review their therapeutic status. Here the treatment of type 1 (non-neuronopathic) Gaucher disease is evaluated with particular reference to the emerging role of oral N-butyldeoxynojirimycin (miglustat) as a substrate-reducing agent. This position statement represents the consensus viewpoint of an independent international advisory council to the European Working Group on Gaucher Disease.

Can oncologists detect distress in their out-patients and how satisfied are they with their performance during bad news consultations?

Recognition of psychological distress in patients with cancer, some of which can be ameliorated with appropriate intervention, is a crucial aspect of patient care. Previous studies, with the exception of one, indicate that oncologists often fail to detect general distress and do not identify those patients with significant psychological disorder. As approximately 25-30% of patients experience anxiety and/or depression severe enough to merit psychological intervention, this is a serious problem. This study assessed the ability of five oncologists to recognise distress in newly referred out-patients who were receiving bad news. Self-report measures of the oncologists' satisfaction with their performance during the bad news interviews were also collected. Each patient had two clinical interviews in which information concerning diagnosis and treatment were given. Prior to each interview patients reported their own levels of distress by completing two self-report questionnaires. These were correlated with the ratings of distress and satisfaction made by each clinician on a visual analogue scale after each interview. Only one oncologist's ratings consistently correlated with patients' self-reported scores. The clinicians tended to under-rate the distress in their patients and were mostly satisfied with their performances during each interview. The ability to detect distress varied between each clinician and confirmed the conclusions of past studies that oncologists would benefit from up-grading their psychological assessment skills.

Investigation into the increase in hay fever and eczema at age 16 observed between the 1958 and 1970 British birth cohorts

OBJECTIVE

To investigate whether changes in certain perinatal and social factors explain the increased prevalence of hay fever and eczema among British adolescents between 1974 and 1986.

DESIGN

Two prospective birth cohort studies.

SETTING

England, Wales, and Scotland.

SUBJECTS

11,195 children born 3-9 March 1958 and 9387 born 5-11 April 1970.

MAIN OUTCOME MEASURES

Parental reports of eczematous rashes and of hay fever or allergic rhinitis in the previous 12 months at age 16.

RESULTS

The prevalence of the conditions over the 12 month period increased between 1974 and 1986 from 3.1% to 6.4% (prevalence ratio 2.04 (95% confidence interval 1.79 to 2.32)) for eczema and from 12.0% to 23.3% (prevalence ratio 1.93 (1.82 to 2.06)) for hay fever. Both conditions were more commonly reported among children of higher birth order and those who were breast fed for longer than 1 month. Eczema was more commonly reported among girls and hay fever among boys. The prevalence of hay fever decreased sharply between social classes I and V, increased with maternal age up to the early 30s, and was lower in children whose mothers smoked during pregnancy. Neither condition varied significantly with birth weight. When adjusted for these factors, the relative odds of hay fever (1986 v 1974) increased from 2.23 (2.05 to 2.43) to 2.40 (2.19 to 2.63). Similarly, the relative odds of eczema rose from 2.02 (1.73 to 2.36) to 2.14 (1.81 to 2.52).

CONCLUSIONS

Taken together, changes between cohorts in sex, birth weight, birth order, maternal age, breast feeding, maternal smoking during pregnancy, and father's social class at birth did not seem to explain any of the observed rise in the prevalence of hay fever and eczema. However, correlates of these factors which have changed over time may still underlie recent increases in allergic disease.

Risk of early death and recurrent stroke and effect of heparin in 3169 patients with acute ischemic stroke and atrial fibrillation in the International Stroke Trial

BACKGROUND AND PURPOSE

We sought to investigate the apparently high risk of early death after an ischemic stroke among patients with atrial fibrillation (AF), identify the main factors associated with early death, and assess the effect of treatment with different doses of subcutaneous unfractionated heparin (UFH) given within 48 hours.

METHODS

We studied the occurrence of major clinical events within 14 days among 18 451 patients from the International Stroke Trial, first for all treatment groups combined. Then, among patients with AF, we examined the effects of treatment with subcutaneous UFH started within 48 hours and continued until 14 days after stroke onset.

RESULTS

A total of 3169 patients (17%) had AF. Seven hundred eighty-four patients were allocated to UFH 12 500 IU SC BID, 773 to UFH 5000 IU SC BID, and 1612 to no heparin. Within each of these groups, half of the patients were randomly assigned to aspirin 300 mg once daily. Compared with patients without AF, patients with AF were more likely to be female (56% versus 45%), to be old (mean age, 78 versus 71 years), to have an infarct on prerandomization CT (57% versus 47%), and to have impaired consciousness (37% versus 20%). The initial ischemic stroke type was more often a large-artery infarct (36% versus 21%). A lacunar stroke syndrome was less common (13% versus 26%). Death within 14 days was more common in patients with AF (17% versus 8%) and more often attributed to neurological damage from the initial stroke (10% versus 4%). The frequency of recurrent ischemic or undefined stroke was not significantly different (3.9% versus 3.3%). The proportion of AF patients with further events within 14 days allocated to UFH 12 500 IU (n=784), UFH 5000 IU (n=773), and to no-heparin (n=1612) groups were as follows: ischemic stroke, 2.3%, 3.4%, 4.9% (P=0.001); hemorrhagic stroke, 2.8%, 1.3%, 0.4% (P<0.0001); and any stroke or death, 18.8%, 19.4% and 20.7% (P=0.3), respectively. No effect of heparin on the proportion of patients dead or dependent at 6 months was apparent.

CONCLUSIONS

Acute ischemic stroke patients with AF have a higher risk of early death, which can be explained by older age and larger infarcts but not by a higher risk of early recurrent ischemic stroke, although slightly more patients with AF died from a fatal recurrent stroke of ischemic or unknown type (1.3% versus 0.9%). In patients with AF the absolute risk of early recurrent stroke is low, and there is no net advantage to treatment with heparin. These data do not support the widespread use of intensive heparin regimens in the acute phase of ischemic stroke associated with AF.