The role of Mycobacterium avium subsp paratuberculosis (MAP) in the etiology and pathogenesis of inflammatory bowel disease (IBD) including Crohn's Disease (CD), has been investigated. The fastidious characteristics and cross reactivity of MAP with other members in Mycobacteria have produced significant challenges in their detection and identification. In this two year pilot study, an array of three PCR molecular assays based on the detection of sequences from the16S rRNA, IS1245, and IS900 genes, belonging to members of the MAC, have been developed and optimized into a common protocol to be used as a rapid and accurate diagnostic tool regarding M. avium complex (MAC) infection. The PCR protocol time was reduced by half, and the sensitivity and specificity of the molecular assays has been significantly improved barring the need for southern hybridization. This improved methodology was employed for the molecular typing of MAC in 100 resected, full-thickness tissue samples removed from IBD patients. The tissue samples were homogenized, decontaminated, and inoculated into two mycobacterial culture media systems. A total of 328 Bactec and Mycobacteria Growth Indicator Tube (MIGT) cultures were evaluated for positive MAC growth. Harvested cells were then subjected to genomic DNA extraction and subsequent PCR typing. The I6 S rRNA-based PCR resulted in detection of 26/28 (93%) MAC in Bactec cultures. Specifically, 25/28 (89%) of positive MAC indicated the presence of IS1245 specific to M. avium subsp avium (MAV), and 6/28 (21%) produced results consistent with the presence of IS900 following nested PCR. Moreover, 20/100 (20%) of MGIT cultures were positive for MAP. Sequence analysis was performed on amplified regions of the IS900 element from seven isolates. A nucleotide alignment revealed that 2/7 isolates demonstrated 100% homology to Bovine MAP and 5/7 isolates showed 96-99% homology to sequenced Bovine MAP published in GenBank. The detection of at least two Bovine derived MAP in IBD tissue will have great impact on the epidemiology and reclassification of IBD. The significant homology of the other five isolates to Bovine derived MAP suggests a diversity in the geographical distribution of MAP regarding Johne's disease and CD. Ultimately, the etiology, diagnosis, and the treatment of IBD as well as control and prevention measures may be enhanced with better tools for investigating emerging infectious diseases.

Despite the chronic debate in the etiology of crohn's disease (cd), a debilitating inflammatory bowel disease (ibd) closely related to ulcerative colitis (uc), an emerging interest in a possible mycobacterial role has been marked. Granuloma and pathologic manifestations in cd resemble aspects found in tuberculosis, leprosy and paratuberculosis. The latter, a chronic enteritis in cattle, goat, sheep and primates, which is similar to human enteritis, also known as cd, is caused by a fastidious, slow growing mycobacterium avium subspecies paratuberculosis (map). Due to the similarities between cd and paratuberculosis, a mycobacterial cause in cd has been proposed. Recent discovery of a possible association between nod2/card15 mutations and risk of cd added support to microorganism-host interactions. In this study, a possible mycobacterial role in cd etiology has been evaluated by investigating the presence of map dna, the state of the cellular immune response and microarray gene expression profiling in peripheral blood and surgical tissue from cd, uc and healthy control subjects. Nested pcr detected map dna in tissue from 10/12(83%) cd patients compared to 1/6(17%) non-ibd subjects. Fluorescence in situ hybridization (fish) with the aid of confocal scanning laser microscopy (cslm) detected map dna in 8/12(67%) cd subjects compared to 0/6(0%) in non-ibd subjects. The detection of map dna by either technique in tissue from cd subjects is significant compared to non-ibd subjects (p < 0.05). Map dna was also detected in both inflamed and non-inflamed tissue from patients with cd suggesting map infiltration in human tissue. Correlation of possible map presence and the function of polymorphonuclear leukocytes (pmn) and peripheral blood mononuclear cells (pbmc) in 19 cd patients and 12 controls have been evaluated. Pmn phagocytosis of viable fitc-map was suppressed in 13/19(68%) cd patients compared to 0/12(0%) in healthy controls (p<0.05). Pbmc phagocytosis of viable fitc-map was suppressed in 5/19(26%) of cd patients compared to 0/12(0%) of healthy controls (p<0.05). The proliferative response of pbmc with t-cell majority from cd and controls subjects was evaluated against pha, candida albicans, pwm and map ppd. Dysfunctional proliferative response against pha was found in 8/19(42%) cd patients compared to 1/12(8.3%) in controls suggesting possible t-cell anergy. Pbmc from 11 cd subjects reacted normally to pha, 7/11(64%) reacted strongly to map ppd suggesting previous exposure to mycobacteria, and 3/11(27%) did not react with map ppd suggesting lack of pre-exposure to mycobacteria. From the seven mycobacterial pre-exposed samples, 6/7(86%) showed a normal ability to recall antigens by activated macrophages when exposed to c. Albicans, and all 7 samples had a normal pwm response. Finally, microarray-chip technology was employed to identify the expression profile of genes that have a role in the immune response of cd patients. Rna was isolated from fresh buffy coats from 8 healthy controls, 2 cd, and 1 uc patients. Chips with an estimated of 30,000 human genes were hybridized to cdna from these samples. We found that 17% of the total number of genes was differentially expressed. Over 200 genes were involved in the immune response, 7 genes where common to both forms of ibd (uc and cd), and 8 genes were found to be either downregulated in cd and upregulated in uc or viceversa. The ifngr1 gene, which encodes the ligand-binding chain of the ifn-gamma receptor, was found to be downregulated in 2/2(100%) of cd patients, but not in uc patients. It is known that defects in ifngr1 are a cause of atypical mycobacterial infection and bcg infection. Patients suffering from this deficiency have an immunologic defect predisposing them to infection with mycobacteria. This correlates with the proposed theory as map being the causative agent of cd. Furthermore, the results indicate a host susceptibility requirement for the establishment of mycobacterial infection in cd patients. Further characterization of ifngr1 using real-time pcr is underway. Collectively, detection of map dna in the majority of cd tissue and the alteration in pmn and pbmc to respond efficiently to map may be related to the fact that mycobacterial pathogens infect phagocytic cells of susceptible hosts and consequently the immune response is dysregulated. Furthermore, the fact that a gene linked to mycobacterial susceptibility was found to be downregulated in cd patients only, strengthens the mycobacterial etiology of cd. In general, the data suggest a possible role for a bacterial pathogen in cd pathogenesis.

Association of Mycobacterium avium subspecies paratuberculosis (MAP) with Crohn's disease (CD) and not with ulcerative colitis (UC), two forms of inflammatory bowel disease (IBD), has been vigorously debated in recent years. This theory has been strengthened by recent culture of MAP from breast milk, intestinal tissue and Blood from patients with active Crohn's disease. Culture of MAP from clinical samples remained challenging due to the fastidious nature of MAP including its lack of cell wall in infected patients. The advent of real time PCR has proven to be significant in infectious disease diagnostics. In this study, real time reverse transcriptase PCR (RT-PCR) assay based on targeting mRNA of the IS900 gene unique to MAP has been developed. All variables included in RNA isolation, cDNA synthesis and real time PCR amplification have been optimized. Oligonucleotide primers were designed to amplify 165 bp specific to MAP and the assay demonstrated sensitivity of 4 genomes per sample. In hope this real time RT-PCR may aid in the detection of viable MAP cells in Crohn's disease patients, a total of 45 clinical samples were analyzed. Portion of each sample was also subjected to 12 weeks culture followed by standard nested PCR analysis. The samples consisted of 17 cultures (originated from 13 CD, 1 UC and 3 NIBD subjects), 24 buffy coat blood (originated from 7 CD, 2 UC, 11 NIBD and 4 healthy subjects) and 4 intestinal biopsies from 2 CD patients. Real time RT-PCR detected viable MAP in 11/17 (65%) of iii suspected cultures compared to 12/17 (70%) by nested PCR including 77% and 84% from CD samples by both methods, respectively. Real time RT-PCR detected MAP RNA directly from 3/7 (42%) CD, 2/2 (100%) UC and 0/4 healthy controls similar to results following long term culture incubation and nested PCR analysis. Interestingly, real time RT-PCR detected viable MAP in 2/11 (13%) compared to 4/11 (26%) by culture and nested PCR in NIBD patients. For tissue samples, real time RT-PCR detected viable MAP in one CD patient with the culture outcome remains pending. This study clearly indicates that a 12-hr real time RT-PCR assay provided data that are similar to those from 12 weeks culture and nested PCR analysis. Consequently, use of real time In our laboratory, we previously demonstrated a possible downregulation in the Interferon-gamma receptor gene (IFNGR1) in patients with active Crohn's disease using microarray chip analysis. In this study, measurement of RNA by real time qRT-PCR indicated a possible downregulation in 5/6 CD patients compared to 0/12 controls. The preliminary data suggest that downregulation in INFGR1 gene, and the detection of viable MAP in CD patients provides yet the strongest evidence toward the linkage between MAP and CD etiology.

BACKGROUND: Vitamin D deficiency and insufficiency are rising healthcare concerns in the United States (US) and worldwide. The latest data collected by the National Health and Nutrition Examination Surveys (NHANES) between 2002-2006 showed that approximately one third of Americans over one-year-old were vitamin D deficient (serum 25-hydroxy vitamin D (25-OHD) < 12 ng/mL) or insufficient (serum 25-OHD < 20 ng/mL) (Looker et al., 2011). Environmental exposures, acute or chronic disease, and genetics can exacerbate vitamin D deficiency. People with malabsorptive disorders such as Inflammatory Bowel Disease (IBD) are at an even greater risk of becoming vitamin D deficient. Pediatric patients with IBD are particularly vulnerable to the short and long-term effects of vitamin D deficiency, given the prominent role played by this agent on skeletal development. More recent data have demonstrated that vitamin D also plays an important role in maintaining and regulating the immune system. For this reason, investigators have been interested in a better understanding of the relationship between vitamin D and inflammation. Vitamin D may prove to be an important adjunct therapy for people suffering from IBD and other autoinflammatory diseases. OBJECTIVES: Many patients and medical providers understand the importance that vitamin D has in a growing child’s skeletal development. However, compliance with daily supplementation remains low. The design of this study allows patients to receive high-dose vitamin D supplementation during scheduled biologic infusions. The goal is to assess the safety and efficacy of high-dose interval vitamin D therapy. The secondary goal of this study will be to determine if optimal vitamin D levels impact the inflammation observed in the gastrointestinal (GI) tract of patients with IBD. METHODS: 60 patients with IBD, between 5-25 years of age, who received regularly scheduled infliximab or vedolizumab infusions, and had serum 25-OHD levels below 30 ng/mL were recruited for the study. These patients were screened for the exclusion criteria, including underlying liver or kidney disease. Enrolled participants were given eight high-dose oral vitamin D3 supplements during scheduled infliximab or vedolizumab infusions for 8-16 months. Serum 25-OHD levels, urine calcium and creatinine levels, and research blood samples were collected at baseline, midpoint, and final visits. Questionnaires were also dispensed to patients to measure quality of life (QoL). This data was collected and analyzed to assess the safety and efficacy of high-dose interval vitamin D supplementation in pediatric patients with IBD. RESULTS: The data from this study showed statistical significance in the change of serum-25OHD level from baseline to midpoint and final visits. The mean increase from baseline to midpoint was 15.71±10.1 ng/mL for the 30 participants who had completed 3 study doses (2,500 mCg or 5,000 mCg) (mean±95% CI). The mean increase from baseline to final visit was 18.1±11.67 ng/mL for the 19 participants who completed all 7 study doses (2,500 mCg or 5,000 mCg) (mean±95% CI). A single factor ANOVA test confirmed statistical significance with p < 0.0001. Urine calcium and creatinine levels did not have a statistically significant change from baseline to final visit for the 12 participants who had completed both samples. Lastly, IMPACT-III QoL scores were not significantly different from baseline. However, there was an overall increase in the mean scores in all 6 subcategories of the survey. As more participants complete the study, the statistical significance and the validity of results will likely be strengthened. CONCLUSION: High-dose interval vitamin D supplementation was a safe and effective way to achieve serum 25-OHD levels to an optimal range (i.e., 40-60 ng/mL) in pediatric patients and young adult patients with IBD. The data suggests that three doses of high-dose vitamin D may be sufficient to bring levels to an optimal and stable plateau. Patient compliance with supplementation was 100% in this study, because of provider-observed ingestion of vitamin D. Patients also noted that this was their preferred method of supplementation. The safety and efficacy results of this study serve as a framework for developing a more standard approach to vitamin D supplementation for our patients with IBD. Future studies may benefit from expanding this method of delivery to patients who have other inflammatory diseases that require both regular oral vitamin D therapy and in person visits for treatments (i.e., intravenous (IV) medication).

No description available.

Bakgrund: Majoriteten av de som drabbas av inflammatorisk tarmsjukdom är kvinnor. Att drabbas vid ung ålder kan öka problematiken. Det finns luckor i forskningen om de psykosociala faktorernas inverkan. Kronisk sjukdom skapar ofta lidande och för att kunna hantera det på ett värdigt sätt krävs kunskap och förståelse. Patienternas erfarenheter om sin sjukdom genererar en bättre inblick och ökad förståelse för sjuksköterskan. Kunskapen hjälper sjuksköterskor att erbjuda god vård för att patienten ska kunna uppleva en så bra livskvalité som möjligt. Syfte: Syftet med denna studie var att belysa unga kvinnors erfarenheter av att leva med en kronisk inflammatorisk tarmsjukdom. Metod: Datamaterialet analyserade med kvalitativ innehållsanalys. Data samlades genom 10 bloggar. Resultat: Ur analysen framträdde fyra kategorier: Vardagen begränsas, Lära sig leva med sjukdom, Kosten styr, Nöjda trots en bristande sjukhusorganisation och åtta underkategorier. Konklusion: Sjuksköterskans ökade kunskap och förståelse kring unga kvinnors erfarenheter av att leva med inflammatorisk tarmsjukdom är av stor vikt för att kunna erbjuda en god och individanpassad omvårdnad. Sjuksköterskans förståelse för patienten bidrar även till en stärkt vårdrelation och sjuksköterskan kan då ge den stöttning patienten efterfrågar.

No description available.

Les manifestations orales de la maladie de Crohn sont bien établies chez les adultes. Toutefois, aucune étude ne s’est concentrée sur les manifestations orales pathologiques chez la population infantile. En ce qui concerne la santé dentaire, très peu d’études ont évalué la prévalence de carie chez les patients atteints de la maladie de Crohn. Les objectifs de cette étude sont de décrire les manifestations orales des enfants et des adolescents atteints de la maladie de Crohn et tout lien possible avec le stade de la maladie (active ou rémission) ainsi que de déterminer s’il existe un lien entre la prévalence de carie et le score de potentiel cariogène de la diète des patients. Hypothèses • Les manifestations buccodentaires décrites chez les adultes sont présentes chez les enfants et adolescents du groupe de Ste-Justine. • Il existe différentes manifestations propres à la population infantile. • L’indice carieux des enfants atteints de la maladie de Crohn est supérieur à celui des enfants en bonne santé. • L’indice de potentiel cariogène est élevé chez les patients atteints de la maladie de Crohn • Le stade de la maladie influence la prévalence des manifestations. Méthodologie Un certificat d’éthique à la recherche fut obtenu de l’hôpital Ste-Justine. Sur 40 patients recrutés, 21 sujets (9 filles, 12 garçons) âgés de 5,1 à 17,3 ans ont participé à l’étude de type transversale. Un questionnaire médical, un examen buccal complet, l’analyse des journaux alimentaires ainsi qu’une revue des dossiers médicaux a permis d’établir la prévalence des lésions pathologiques, la prévalence de carie (indice CAO) et le score de potentiel cariogène (SPC) selon la méthode du Dre Monique Julien. Résultats Les analyses statistiques démontrent: • Aucune différence significative entre le CAO des patients atteints de la maladie et celui du groupe contrôle. • Aucune manifestation orale autre que celles présentées dans la littérature. • 57% des patients ont rapporté avoir eu des ulcères buccaux au cours de la maladie. • Les patients en phase active ne sont pas différents de ceux en rémission en ce qui concerne les manifestations orales, le CAO et le SPC. • Les enfants qui prennent du méthotrexate ont un CAO plus élevé. • Les patients qui ont plus de caries n’ont pas nécessairement une diète plus cariogène. Conclusion Selon les résultats de notre étude, nous n’avons pas observé de manifestations orales propre à la population infantile. De plus, les enfants atteints de la maladie ne semblent pas être un groupe à risque de carie dentaire. Davantage d’études sont nécessaires sur les manifestations orales de la maladie de Crohn chez la population pédiatrique. / Oral manifestations of Crohn’s disease are well documented in adults. However, no studies have investigated the oral manifestations of this condition in children and adolescents. Regarding oral health, only a few studies have evaluated the prevalence of dental caries in these patients. The objectives of this study are to describe the oral manifestations of Crohn’s disease in children and establish a link between the state of the disease (active and in remission) with the prevalence of dental caries and the cariogenicity of the diet of these children. Hypotheses • The oral manifestations described in adults are present in children and adolescents of the Ste-Justine group. • There are different oral manifestations in children. • Children with Crohn’s disease have more dental caries than children in good health. • The cariogenicity index of the diet is high in patients with Crohn’s disease • The state of the disease has an effect on the prevalence of the oral manifestations. Methodology An ethic’s certification was obtained from Ste-Justine Hospital. Of 40 recruited patients, 21 patients (9 girls, 12 boys) ranging in age from 5.1 to 17.3 years of age participated in our transversal study. A medical history, a complete oral exam, a diet analysis and a review of the medical chart gave us the opportunity to record the presence of oral manifestations, the prevalence of dental caries (DMFT) and the cariogenicity score (SPC). The DMFT of Crohn’s disease patients was compared with the DMFT of Quebec children establish in the Dr. Brodeur epidemiological study conducted in 1996. The patients were also divided into two groups according to the state of the disease (active or remission) to evaluate if it affected the prevalence of oral lesions, the DMFT and the SPC. Results The statistics show : • No significant difference between the DMFT of Crohn’s disease patients and the control group. • No oral manifestations other than those published in the adult literature. • 57% of patients reported to have ulcers at some time during the disease • The patient in the active phase is not different then those in remission ones regarding oral manifestations, DMFT and SPC. • Children taking methotrexate have a higher DMFT • Patients with a higher DMFT do not necesserarily have a higher SPC Conclusion The results of our study do not demonstrate any new oral manifestations in Crohn’s disease in children that have not already been described in adults. In addition, children with Crohn’s disease do not seem to be at high risk for dental caries. Further studies are necessary on the oral manifestations of Crohn’s disease in the pediatric population.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

Introdução: Pacientes com Doença de Crohn (DC) apresentam alto risco de eventos tromboembólicos (TE), muitas vezes, associados a alta morbimortalidade. É conhecido o papel da inflamação na fisiopatologia da trombose na doença Inflamatória Intestinal (DII), entretanto, o significado da inflamação subclínica ainda se mantém obscuro na literatura. Este estudo avaliou o efeito da atividade endoscópica no perfil de coagulação dos pacientes com DC em remissão clínica. Métodos: entre os dias 22 de maio de 2015 e 26 de abril de 2017, foram triados 261 pacientes com DC em possível remissão clínica, sendo realizadas ao todo 229 colonoscopias. Das 229 colonoscopias realizadas, 164 pacientes estavam realmente em remissão clínica (confirmados com CDAI <= 150) e foram alocados em dois grupos: 75 no grupo de atividade endoscópica (AE) (SES-CD >= 7), 89 no grupo de remissão endoscópica (RE) (SES-CD <= 2). Cinquenta controles saudáveis pareados por sexo e idade foram eleitos. Medimos, nos 3 grupos, além da geração de trombina - pelo método Calibrated Automated Thrombogram (CAT), com e sem trombomodulina, - a atividade do fator tecidual (FT), fibrinogênio, D-dímero, Fator VIII, ADAMTS-13, Fator de von Willebrand - antígeno e cofator de ristocetina (cWF). Coletamos dados sobre a duração da doença, extensão, comportamento, localização, tratamento farmacológico, história prévia de cirurgias, calprotectina fecal, qualidade de vida (por meio do IBDQ), além dos fatores de risco para TE, como hospitalização recente, uso de corticoide atual, status do tabagismo, assim como marcadores de trombofilia hereditária ou adquirida. Seguimos os pacientes por 1 ano de observação, avaliando a variação no CDAI e IBDQ no período. Resultados: A maioria dos pacientes apresentou comprometimento ileocolônico (43%), com comportamento inflamatório (40%), seguido de estenosante (30%) e fistulizante (30%). 67% estavam em uso de imunossupressores e 52% em uso de biológicos. Os fatores de risco para TE e todos os outros marcadores de trombofilia, incluindo deficiência de proteína C e S, anticardiolipina, resistência à proteína C, antitrombina, mutações da protrombina e do Fator V, foram semelhantes em ambos os grupos, exceto pelo anticoagulante lúpico, maior no grupo de AE (8,1% vs. 1,3%, p=0,047). Como esperado, o grupo de AE apresentou níveis significativamente maiores de PCR, calprotectina fecal e plaquetas. Além disso, este grupo apresentou uma maior atividade do fator tecidual vs. o grupo de RE vs. controles (127 vs. 103 vs. 84, p = 0,001). Embora o grupo DC tivesse maiores níveis de FVW:Ag e FVW:RCo, FVW/ADAMTS-13, Fator VIII e trombomodulina vs. controles, não houve diferença estatística entre os grupos de AE e RE. Os níveis de geração de trombina foram semelhantes entre os 3 grupos, com ou sem trombomodulina. Conclusão: Esses dados evidenciam que existe uma disfunção endotelial inerente à DC, e, que, em pacientes com AE, essa disfunção pode ser ainda maior pela maior exposição do FT. Embora, a presença de inflamação e dano endotelial contribuam para esse estado procoagulante, em pacientes com doença subclínica, há um estado de compensação permanente, uma vez que a quantidade de trombina gerada foi a mesma entre os grupos. Este equilíbrio pode estar comprometido diante de outros fatores tromboembólicos, aumentando, assim, o risco de trombose / Background: Crohn\'s disease patients (CD) have a high risk of thromboembolic events (TE), often associated with high morbidity and mortality. Involvement of inflammation in TE is well known, but significance of the sub-clinical inflammation in this process is not the rule. Thus, the aim of this study is to evaluate the effect of the endoscopic activity in the coagulation profile in CD in clinical remission. Methods: Between May/2015 and April/2017, 261 CD patients in supposed clinical remission, were screened, and 229 had a colonoscopy done, resulting in the inclusion of 164 CD patients in clinical remission confirmed by a CDAI <= 150. They were allocated in two groups: 75 in the endoscopic activity (EA) group (SES-CD >= 7), and 89 in the endoscopic remission (ER) group (SES-CD <= 2). 50 healthy controls matched for sex and age were chosen. We measured in the 3 groups, in addition to the generation of thrombin - through the Calibrated Automated Thrombogram (CAT), with and without thrombomodulin, - the activity of tissue factor (TF), fibrinogen, D-dimer, Factor VIII, ADAMTS-13 and von Willebrand Factor - antigen (VWF) and ristocetin cofactor (VWF:RCo). We collected data regarding the duration of the disease, extension, behavior, location, pharmacological treatment, previous history of surgeries, fecal calprotectin, quality of life (through IBDQ), as well as risk factors for TE such as recent hospitalization, current corticoid use, smoking status, as well as markers of hereditary or acquired thrombophilia. We followed the patients for 1 year of observation, evaluating the variation in CDAI and IBDQ. Results: Most of the patients had ileocolonic involvement (43%), with inflammatory behavior (40%), followed by stenosing (30%) and fistulizing (30%). 67% were in use of immunosuppressors and 52% in use of biological drugs. Risk factors for TE besides other markers of thrombophilia, including protein C and S deficiency, anticardiolipin, protein C resistance, antithrombin, prothrombin and Factor V mutations, were similar in both groups except for the lupus anticoagulant, higher in the EA group (8.1% vs. 1.3%, p = 0.047). As expected, the EA group had significantly higher levels of CRP, fecal calprotectin and platelets. In addition, this group had a higher activity of TF vs. ER group vs. controls (127 vs. 103 vs. 84, p = 0.001). Although the DC group had had higher levels of VWF and VWF:RCo, VWF/ADAMTS-13, Factor VIII and thrombomodulin vs. controls, there was no statistical difference between the EA and ER groups. Thrombin generation levels were similar between the 3 groups, with or without thrombomodulin. Conclusion: These data show that there is an inherent endothelial dysfunction in CD, moreover in patients with EA, this dysfunction may be even greater, due to the exposure of TF. Although the presence of inflammation and endothelial damage contribute to this procoagulant condition, in patients with subclinical disease, there is a permanent compensatory state, since the amount of thrombin generated was the same between the groups. This balance may be compromised by other thromboembolic factors, thus increasing the risk of thrombosis