Contexte: L’hémorragie intraventriculaire néonatale est associée à des séquelles neuro-développementales, mais le risque à long terme d'autres issues est inconnu. L'association entre l'hémorragie intraventriculaire néonatale et le risque de morbidité durant l’enfance a été évaluée. Méthodes: Une cohorte longitudinale de 794,384 bébés nés entre 2006 et 2016 au Québec, Canada a été analysé. Les nouveau-nés ont été suivis jusqu'à une période de 12 ans après leur naissance, pour identifier les hospitalisations subséquentes. Dans les modèles de régression de Cox, ajustés pour les caractéristiques maternelles et néonatales, les « hazard ratios » et intervalles de confiance (IC) à 95% ont été estimés pour l'association entre l'hémorragie intraventriculaire avec l’hospitalisation ultérieure. Résultats: Au total, 1,322 nourrissons (0,2%) ont développé une hémorragie intraventriculaire de grade I à IV. L'incidence de l'hospitalisation était plus élevée chez les bébés présentant une hémorragie intraventriculaire que chez les bébés sans hémorragie (23,8 vs 5,7 par 100 personnes-années). Comparés aux bébés sans hémorragie, les bébés affectés avaient un risque d'hospitalisation 1,56 fois plus élevé (IC à 95% 1,43-1,70). Le risque était 2,81 fois plus élevé pour les grades III/IV (IC à 95% 2,23 à 3,53) comparés à ceux nés sans hémorragie. Les hémorragies intraventriculaires pré-terme était associée à 1,82 fois le risque (IC 95% 1,66-2,00) comparés aux bébés nés termes sans hémorragie. Les hémorragies intraventriculaires à terme étaient associées à 3,19 fois le risque d'hospitalisation (IC 95% 2,55-4,00), comparativement à ceux nés termes sans hémorragie. Les raisons principales des hospitalisations comprenaient les maladies du système nerveux central, ophtalmologiques, musculo-squelettiques et cardiovasculaires. Conclusion: L'hémorragie intraventriculaire, notamment de grades sévères et parmi les bébés à terme, est un déterminant important du futur risque d’hospitalisation durant l’enfance. / Background: Neonatal intraventricular hemorrhage is associated with neurodevelopmental sequelae, but the long-term risk of other outcomes is unknown. The association between neonatal intraventricular hemorrhage and the risk of childhood morbidity was assessed. Methods: A longitudinal cohort of 794,384 infants born between 2006 and 2016 in Quebec, Canada was analyzed. Infants were tracked over time to identify later hospitalizations with follow-up extending up to 12 years after birth. In Cox regression models adjusted for maternal and infant characteristics, the hazard ratios and 95% confidence intervals (CI) were estimated for the association of intraventricular hemorrhage with future hospitalization. Results: A total of 1,322 (0.2%) infants developed grade I to IV intraventricular hemorrhage. The incidence of childhood hospitalization was higher in infants with intraventricular hemorrhage than in infants without hemorrhage (23.8 vs. 5.7 per 100 person-years). Compared with no hemorrhage, infants with intraventricular hemorrhage had 1.56 times the risk of hospitalization (95% CI 1.43-1.70). The risk was 2.81 times higher for grade III/IV hemorrhage (95% CI 2.23-3.53) compared to those born without hemorrhage. Preterm intraventricular hemorrhage was associated with 1.82 times the risk (95% CI 1.66-2.00) compared to term infants born without hemorrhage. Intraventricular hemorrhage at term was associated with 3.19 times the risk of hospitalization (95% CI 2.55-4.00) compared to those born term without hemorrhaging. Primary reasons for hospitalizations included central nervous system, ophthalmologic, musculoskeletal, and cardiovascular disorders. Conclusion: Intraventricular hemorrhage, especially of higher grades and in term neonates, is an important determinant of the future risk of child hospitalization.

Adrenal gland insufficiency – the clinical manifestation of deficient production or action of adrenal steroids – is a life-threatening disorder. Among many factors which can predispose to primary adrenal failure, an autoimmune adrenalitis and infectious agents play a major role. The initial host defense against bacterial infections is executed primarily by the pattern recognition receptors, e.g. Toll-like receptors (TLRs), expressed in cells from the innate immune system. Upon activation, TLRs have been found to regulate various levels of innate and adaptive immunity as well as control tissue inflammation. TLRs are implicated in adrenal cell turnover and steroidogenesis during inflammation. Therefore, TLRs play a crucial role in the activation of adrenal inflammation mediating adrenal gland dysfunction during septicemia. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Einleitung Die aneurysmale Subarachnoidalblutung und ihre Komplikationen stellen eine akut lebensbedrohliche Erkrankung dar. Aufgrund einer hohen Letalität und Morbidität sowie zahlreichen, nicht modifizierbaren Risikofaktoren und fehlenden eindeutigen Präventionsmaßnahmen bleibt diese Krankheit eines der aktuellen Themen der Neurochirurgie. Ziel Ziel dieser Studie ist der Vergleich der Behandlungsergebnisse von Patienten mit aneurysmaler SAB im Klinikum Chemnitz mit aktuellen Literaturdaten. Material und Methode In dieser Arbeit wurden die Daten von insgesamt 200 Patienten mit aneurysmaler Subarachnoidalblutung retrospektiv zusammengefasst. Es wurde eine Populationsanalyse zusammen mit einer Analyse der Korrelationen zwischen verschiedenen Ausgangs- und Verlaufsparametern mit dem allgemeinen Outcome und der Mortalität durchgeführt. Zusätzlich erfolgte eine Follow-up-Analyse der Mortalität und Morbidität bei 108 Patienten. Im statistischen Modell wurden eine Uni- und Bivariatanalyse sowie binäre und multinomiale logistische Regression angewendet. Kaplan-Meier-Kurven in Verbindung mit Cox-Regressionsanalysen wurden zur Beurteilung der Mortalität eingesetzt. Die Ergebnisse wurden mit Literaturdaten verglichen. Das Votum der Ethikkommission der TU Dresden liegt vor (EK 181052014 vom 15.09.2014). Ergebnisse Von 200 Patienten mit einem Durchschnittsalter von 52 J (20-82 J, Medianalter 51 ± 13,6 J) waren 69 Patienten männlich (34,5 %), 131 – weiblich (65,2 %). Das männlich : weiblich Verhältnis betrug 1:1,9. Der klinische Schweregrad der Patienten bei Aufnahme wurde durch die WFNS- und die HH-Skalen evaluiert. Zusätzlich wurden die BNI- und Fisher-Skalen zwecks Evaluation des radiologischen Schweregrades der aSAB eingesetzt. Die Patientendistribution anhand der WFNS-Skala war: WFNS °I – 42,0 %, WFNS °II – 10,0 %, WFNS °II – 16,5 %, WFNS °IV – 22,5%, WFNS °V – 9,0 %. Die Verteilung der Patienten durch die HH-Skala war vergleichbar. 14,5 % der Patienten hatten eine BNI 1, 41,5 % - BNI 2, 32,0 % – BNI 3, 10,5 % - BNI 4, 1,5 % - BNI 5 Blutung. Bei 5,5 % der Patienten lag eine Fisher 1, 10,5 %– Fisher 2, 28,0% - Fisher 3 und 56,0 % - Fisher 4 SAB vor. 77,5 % der Aneurysmata waren klein (<11mm), 18,5 % - groß (11-25mm), 4 % - Giant (>25mm). Die Aneurysmen war meist im Bereich der Acom (41,5 %) und MCA (36,5 %) lokalisiert. Insgesamt 94,5 % der Aneurysmen gehörten zur vorderen Zirkulation. Die primäre Mortalitätsrate betrug 14,5 %. 21,5% der Patienten hatten einen mRS von 0-1 bei Entlassung, 26,0 % - einen mRS 2-3, 38,0 % - einen mRS 4-5. Die mittlere Follow-up-Dauer betrug 71,3 ± 43,2 Monate (Spannweite 2-168 Monate). Von den initial Überlebenden und im Follow-up eingeschlossenen Patienten sind 10,2 % im Verlauf verstorben. 48,1 % hatten einen mRS 0-1, 30,6% mRS 2-3, 11,1 % - mRS 4-5. Diskussion Das Outcome der Patienten mit einer aSAB trägt einen multifaktoriellen Charakter. Die wesentlichen Prädiktoren des Outcomes sind das Alter, der klinische und radiologische Schweregrad der Blutung, die Notwendigkeit der Versorgung eines posthämorrhagischen Hydrozephalus (temporäre und dauerhafte CSF-Ableitung), ein Vasospasmus, DIND und Entgleisun-gen im Serum-Natrium-Spiegel. Die Mortalitätsrate bei der primären Versorgung der Patienten mit einer aSAB in unserer Ko-horte ist um etwa 5 % niedriger als in der Literatur angegeben. Die Mortalitätsrate steigert sich allmählich während der ersten 3 Wochen. Sie wird im Wesentlichen vom Patientengeschlecht, dem klinischen und radiologischen Schweregrad der Blutung, der Notwendigkeit einer Akutversorgung eines aufgetretenen Hydrozephalus, einem Vasospasmus, Entgleisungen im Serum-Natrium-Spiegel sowie der Notwendigkeit einer CSF-Dauerableitung beeinflusst. Die Notwendigkeit einer CSF-Außenableitung bei Aufnahme korreliert mit einem schlechten Zustand der Patienten bei Entlassung und im Follow-up. Der Vasospasmus ist ein unabhängiger Prädiktor eines primär schlechten Outcomes und einer hohen Mortalität, zeigt sich aber als nicht signifikanter Faktor im Langzeit-Follow-up. Die Shuntpflicht ist bei Patienten mit Elektrolytentgleisungen, beidseitigen EVDs und DIND 3-4fach erhöht, beeinflusst jedoch nur die primäre Morbidität/Mortalität. Entgleisungen im Serum-Natrium-Spiegel zeigten sich als unabhängiger Prädiktor eines schlechten Outcomes und erhöhter Mortalität sowohl während des stationären Aufenthaltes, als auch im Langzeit-Follow-up. Die Notwendigkeit einer dekompressiven Kraniektomie wiederspiegelt sich in einem niedrigen BI der Patienten im primären Outcome und ist Prädiktor eines schlechten Outcomes und erhöhter Mortalität im Langzeit-Follow-up.:Verzeichnis der Abkürzungen 5 Kapitel 1: Grundlagen 6 1.1. Einleitung 6 1.2. Definition und Epidemiologie 7 1.3. Ätiologie 8 1.4. Pathogenese 9 1.5. Klinische Manifestation 11 1.6. Diagnostik 13 1.7. Therapie des rupturierten Aneurysmas 15 1.8. Therapie der Komplikationen nach aneurysmaler Subarachnoidalblutung 17 Kapitel 2: Methodik 19 2.1. Allgemein 19 2.2. Patientengut, Aufnahmezustand und Aneurysmacharakterisierungen 20 2.3. Therapie und Krankheitsverlauf 21 2.4. Outcome 22 2.5. Evaluation des aktuellen Zustandes der Patienten 23 2.6. Datenschutz und Statistisches Modell 24 Kapitel 3: Ergebnisse 25 3.1. Populationsanalyse, Ein- und Ausschlusskriterien 25 3.2. Schwere der Subarachnoidalblutung 26 3.3. Charakteristika der rupturierten Aneurysmen 27 3.4. Primäres Outcome 29 3.5. Outcome im Langzeit-Follow-up 31 3.6. Mortalität 33 3.7. Therapiedauer, Hydrozephalus, Elektrolytentgleisungen 36 3.8. DIND und Vasospasmus 38 3.9. Therapieassoziierte Komplikationen und Folgeoperationen 39 Kapitel 4: Diskussion 40 4.1. Mortalität 40 4.2. Outcome 43 4.3. Versorgungspflichtiger Hydrozephalus und Outcome 44 4.4. Vasospasmus, DIND, Elektrolytentgleisungen und Outcome 45 4.5. Limitationen der Studie 47 4.6. Schlussfolgerungen 48 Zusammenfassung 49 Summary 52 Literaturverzeichnis 55 Anlage 1 64 Anlage 2 66 Anlage 3 67 Anlage 4 68 Anlage 5 69 Anhang 1: Mortalitätsdynamik während des stationären Aufenthaltes 72 Anhang 2: Mortalitätsdynamik im Follow-up 74 Anhang 3: Die Abhängigkeit des Outcomes von verschiedenen Faktoren 75 Danksagung 78

Les dernières années ont laissé place à de nombreuses avancées médicales, montrant de plus en plus d’intérêt à l’amélioration des modalités de soin et du cadre de vie des patients, en apportant plus d’efficacité et moins de risque. Dans ce contexte, trois études de recherche clinique ont été menées avec le potentiel microphonique cochléaire (PMC) pour évaluer les capacités de cette réponse cochléaire dans des applications médicales originales et proposer des outils de surveillance de grand intérêt pour la prise en charge des patients. La première étude s’est intéressée à la survenue de surdités suite aux exérèses de neurinome de l’acoustique, notamment les pertes auditives d’origine vasculaire. L’amplitude du PMC a détecté tous les événements chirurgicaux responsables de l’altération de la vascularisation cochléaire et a ainsi fourni une meilleure compréhension de l’origine des pertes auditives lors des chirurgies dans l’angle pontocérébelleux. Les deux autres études ont porté sur la fiabilité d’un monitorage non invasif de la pression intracrânienne (PIC) par la phase du PMC sur une longue période de suivi, chez des patients pour lesquels il est attendu une variation de la PIC. Le PMC a montré une bonne capacité à détecter les variations de la PIC au cours du temps, aussi bien lors d’une installation lente d’une PIC élevée (progression de gliome malin) que lors de l’apparition transitoire et aiguë d’une PIC augmentée (hypertension intracrânienne, hydrocéphalie).Plusieurs observations parfois inattendues ont été obtenues avec le PMC et ouvrent de nouvelles pistes d’intérêt et de réflexion sur les mécanismes de fonctionnement de la PIC ou de la cochlée. Parmi elles : une répercussion épisodique de l’embolisation des anévrysmes cérébraux sur la PIC, l’aptitude de la phase du PMC à prédire la survenue prochaine d’une crise de Menière et la possible prédiction préopératoire d’une fragilité cochléaire au fraisage du conduit auditif interne quand le signal IRM des fluides cochléaires du côté affecté (par le neurinome de l’acoustique) est hypointense. / The last years, healthcare and living conditions of patients have been of growing interest in medical advances with the goal to bring more efficiency and less risk. In this context, three clinical researches have been conducted with cochlear microphonic potential (CMP) to assess the abilities of this cochlear response in unusual medical applications and propose monitoring tools of major interests for patients’ management.The first study is interested in the occurrence of deafness following vestibular schwannoma resection, in particular hearing loss due to vascular origin. The CMP amplitude detected all the surgical events responsible for the alteration of the cochlear vascularization and thus provided a better understanding of the origin of the hearing losses during surgeries in the cerebellopontine angle.The other two studies examined the reliability of non-invasive intracranial pressure (ICP) monitoring, by the CMP phase, over a long period to follow patients for whom a change in ICP is expected. The CMP has shown good ability to detect changes in ICP over time, both in a slow installation of a high ICP (progression of malignant glioma) and in the transient and acute onset of increased ICP (intracranial hypertension, hydrocephalus).Several observations, sometimes unexpected, have been obtained with the CMP and open up new track of interest and reflections on the mechanisms of ICP and cochlea functioning. These discoveries included: episodic repercussion of cerebral aneurysm embolization on ICP, ability of CMP phase to predict the next occurrence of a Meniere crisis, and preoperative prediction of cochlear fragility during the drilling of the internal auditory meatus when the MRI signal of the cochlear fluids on the affected side (vestibular schwannoma) is hypointense.

Human mesenchymal stem cell (MSC) therapy has shown neuroprotective effects and improvement on recovery from neonatal intraventricular hemorrhage (IVH). This study focused on histological evaluations of human amniotic fluid MSC therapy during early prenatal life in a preterm IVH rabbit model. IVH was diagnosed at 24 h of age with ultrasound and animals were randomized into subgroups with confirmed IVH and an IVH negative control group. Animals with confirmed IVH received vehicle only or MSCs at two different doses via intraperitoneal administration. The animals were sacrificed at 48 h post administration. The severity of IVH was histologically analyzed via staining of endogenous peroxidase activity in cryosections and the distribution of red blood cells and cell-free hemoglobin was scored. Primary antibodies targeting human epitopes were validated in IHC assays of frozen MSC pellet. An anti-human nuclear mitotic apparatus (hNuMA) antibody labeled the majority of cells in the MSC pellet and did not cross-react with rabbit NuMA when tested in the nontreated rabbit brain. Significant levels of red blood cells and cell-free hemoglobin were found in the IVH confirmed group, whereas the control group showed no hemorrhage. The MSC therapy groups showed similar scoring results as the IVH-vehicle group. Anti-hNuMA immunolabeling did not detect any cells in the brain of MSC treated rabbits. However, extracellular (nonnuclear) immunolabeling was detected, located in the midbrain of the animals that received MSCs, indicating the presence of MSC nuclear debris. The preterm rabbit model was proven successful for inducing IVH, whereas MSC treatment did not affect the degree of hemorrhage. To increase the possibility to detect the MSCs post administration, future studies should include prelabeling of the MSCs with a suitable cell tracker and analyses at time points closer to the administration of MSCs. / Human mesenkymal stamcellsterapi har visat neuroprotektiva effekter samt förbättring av återhämtning efter neonatal intraventrikulär blödning (IVH). Denna studie fokuserade på histologiska utvärderingar av stamcellsterapi med humana mesenkymala stamceller (MSC) från fostervatten under tidigt prenatalt liv i en prematur IVH-kaninmodell. IVH diagnostiserades med ultraljud vid 24 tim. ålder och djuren delades slumpmässigt in i undergrupper med konfirmerad IVH och en IVH-negativ kontrollgrupp. Djur med konfirmerad IVH mottog endast bärmedel eller MSC i två olika doser via intraperitoneal administration. Djuren avlivades 48 tim. post administration. Graden av IVH analyserades histologiskt genom färgning av peroxidasaktivitet i kryosnitt av hjärna och distributionen av erytrocyter samt fritt hemoglobin graderades. Primärantikroppar riktade mot humana epitop validerades i immunhistokemiska analyser av fryst MSC-pellet. En anti-human nukleär mitotisk apparat (hNuMA) antikropp märkte majoriteten av cellerna i MSC-pelleten och korsreagerade inte med kanin-NuMA under försök i obehandlad kaninhjärna. Signifikanta nivåer av erytrocyter och fritt hemoglobin påvisades i gruppen med konfirmerad IVH, medan kontrollgruppen inte visade någon blödning. Samtliga IVH-grupper; IVH-vehicle och de som mottog MSC- terapi, visade liknande blödningsgrad. Anti-hNuMA-immuninmärkning kunde inte detektera några celler i de MSC-behandlade kaninhjärnorna. Dock detekterades extracellulär (icke-nukleär) immuninmärkning lokaliserad i mitthjärnan hos de djur som mottog MSC, vilket indikerar närvaro av nukleär MSC-debris. Den prematura kaninmodellen bevisades vara framgångsrik för induktion av IVH, men MSC-terapi påverkade inte blödningsgraden. För att öka sannolikheten att detektera MSC efter administration, borde framtida studier inkludera förmärkning av MSC med en lämplig cellmarkör samt analyser vid tidpunkter närmare administrationen av MSC.

The relative risk of major gastrointestinal bleeding (GIB) among different direct oral anticoagulants (DOACs) is debatable. Randomized controlled trials (RCTs) comparing DOACs with each other are lacking. We performed network meta-analysis to assess whether the risk of major GIB differs based on type and dose of DOAC. Literature search of PubMed, EMBASE and Cochrane databases from inception to August 2019, limited to English publications, was conducted to identify RCTs comparing DOACs with warfarin or enoxaparin for any indication. Primary outcome of interest was major GIB risk. We used frequentist network meta-analysis through the random-effects model to compare DOACs with each other and DOACs by dose to isolate the impact on major GIB. Twenty-eight RCTs, including 139 587 patients receiving six anticoagulants, were selected. The risk of major GIB for DOACs was equal to warfarin. Comparison of DOACs with each other did not show risk differences. After accounting for dose, rivaroxaban 20 mg, dabigatran 300 mg and edoxaban 60 mg daily had 47, 40 and 22% higher rates of major GIB versus warfarin, respectively. Apixaban 5 mg twice daily had lower major GIB compared to dabigatran 300 mg (OR, 0.63; 95% CI, 0.44-0.88) and rivaroxaban 20 mg (OR, 0.60; 95% CI, 0.43-0.83) daily. Heterogeneity was low, and the model was consistent without publication bias (Egger's test: P = 0.079). All RCTs were high-quality with low risk of bias. DOACs at standard dose, except apixaban, had a higher risk of major GIB compared to warfarin. Apixaban had a lower rate of major GIB compared to dabigatran and rivaroxaban.

No description available.

No description available.

Objectif : Étudier le risque d’hémorragies intracrâniennes et d’infarctus du myocarde chez les patients vivant avec le VIH. Méthode : J’ai réalisé deux études de cohorte au sein de la banque de données de la Régie de l’assurance maladie du Québec. J’ai défini la cohorte des patients VIH-positifs, y ai étudié l’incidence d’hémorragies intracrâniennes et d’infarctus du myocarde, et l’ai comparée à une cohorte VIH-négative de même âge et de même sexe. J’ai étudié l’association entre ces évènements et l’exposition aux antirétroviraux au moyen d’études cas-témoin nichées dans la cohorte des patients VIH-positifs. Résultats : Le VIH est associé à un risque plus élevé d’hémorragies intracrâniennes, particulièrement au stade SIDA. Les patients VIH-positif sont également plus à risque de subir un infarctus du myocarde, et certains antirétroviraux sont associés à un risque plus grand. Conclusion : Les banques de données médico-administratives représentent un moyen valable d’étudier les comorbidités non-infectieuses chez les patients atteints du VIH. / Objective: To study the risk of intracranial hemorrhage, acute myocardial infarction and their determinants in HIV-infected patients. Methods: I conducted two matched cohort studies within the database of the Régie de l’assurance maladie du Québec. I identified the cohort of HIV-infected patients and compared the incidence of intracranial hemorrhage and myocardial infarction with that in an age and sex matched cohort of HIV-negative patients. To study the association between these events and exposure to antiretrovirals, I conducted two matched case-control studies nested in the HIV-positive cohort. Results: HIV-infected patients had increased risk of developing intracranial hemorrhage, particularly if they had AIDS. They were also at greater risk of suffering from myocardial infarction. Exposure to some antiretroviral drugs was associated with greater risk of myocardial infarction. Conclusion: Administrative health data can be used to study the non-infectious complications of HIV infection, but validation studies are needed to evaluate data quality.

Pacientes envenenados pela serpente Bothrops jararaca manifestam uma tendência hemorrágica em que a plaquetopenia é um achado consistente. Manifestações clínicas sistêmicas, como sangramento de mucosas e microangiopatia trombótica em alguns pacientes, apresentam similaridades com sinais clínicos de doença de von Willebrand e púrpura trombocitopênica trombótica. Algumas proteínas do veneno - como a botrocetina (uma proteína relacionada às lectinas do tipo C) e as metaloproteinases do veneno (SVMP) - interferem direta ou indiretamente na interação entre plaquetas e o fator de von Willebrand (vWF) in vitro e in vivo. E dessa forma, podem contribuir para os sangramentos induzidos pelo envenenamento devido à importância que o vWF tem para a hemostasia primária. Pensando em compreender a participação do vWF do organismo e a botrocetina e as SVMP do veneno bruto de B. jararaca (BjV) na plaquetopenia induzida pelo envenenamento, utilizamos dois modelos experimentais: ratos Wistar heterogênicos e camundongos nocautes do gene Vwf (Vwf-/-). No modelo em ratos, o BjV foi pré-incubado com salina (controle positivo), um inibidor de metaloproteinases (Na2-EDTA), anticorpos policlonais anti-botrocetina, glicerol (veículo dos anticorpos), ou a combinação do Na2-EDTA e anticorpos anti-botrocetina; o grupo controle negativo foi injetado somente com salina. Após a administração subcutânea (s.c.) dos venenos tratados (1,6 mg/kg), amostras de sangue foram coletadas após 3, 6 ou 24 h, e analisaram-se a contagem de plaquetas, quantificação antigênica (vWF:Ag) e da atividade de ligação do vWF ao colágeno (vWF:CB), a atividade de ADAMTS13, a distribuição multimérica de vWF, e a atividade coagulante de fator VIII (FVIII). Para explorar a participação do vWF na plaquetopenia, camundongos nocautes de vWF (Vwf-/-) e camundongos controles (C57BL/6) foram injetados s.c. com BjV incubado com salina (grupo positivo do envenenamento) ou apenas salina (grupo controle negativo). As injeções dos tratamentos, bem como os períodos analisados foram idênticos aos dos ratos. Em nossos resultados, todos os ratos injetados com algum tratamento de BjV, inclusive nos animais que receberam veneno pré-tratado com anticorpo anti-botrocetina e/ou Na2-EDTA, apresentaram plaquetopenia, com maior intensidade em 6 h. Na avaliação do vWF foi encontrada uma grande variação individual nos grupos de tratamentos, porém ainda assim houve uma tendência a redução nos níveis de vWF:Ag em 3 e 6 h nos ratos que receberam BjV sem inibidores. A administração de BjV tratado somente com anticorpo anti-botrocetina promoveu uma maior redução nos níveis de vWF:Ag em 3 h, com retorno aos níveis semelhantes aos de controle negativo em 6 h e 24 h. A inibição sozinha das metaloproteinases não promoveu efeito importante, porém em 6 h, potencializou a ação do anticorpo anti-botrocetina na inibição conjunta do decréscimo de vWF:Ag e vWF:CB. A análise dos multímeros do vWF mostrou perfis bastante variáveis individualmente, porém os multímeros de alto peso molecular e intermediário tenderam a diminuir e os de baixo peso a aumentar nos animais que receberam algum tratamento com BjV, especialmente em 24 h. Na dosagem de FVIII, houve redução em 3 e 6 h em todos os ratos que receberam qualquer tratamento de BjV, sem grandes variações entre esses grupos. A atividade de ADAMTS13 apresentou uma redução dos valores em 3 e 6 h, que foi revertida pela inibição das metaloproteinases do veneno. Já nos camundongos, a plaquetopenia esteve presente em todos os animais nocautes e controles que receberam BjV, mostrando ser independente da presença de vWF. Nos camundongos controles (C57BL/6), não houve alterações evidentes em vWF:Ag durante o envenenamento, porém em 3 h houve uma tendência a sua diminuição. Em conjunto, nossos resultados mostram que a presença da botrocetina no veneno bruto não afeta a plaquetopenia desencadeada pelo envenenamento, porém influencia o vWF plasmático quantitativa e funcionalmente. As metaloproteinases do veneno têm forte efeito sobre a enzima fisiológica reguladora da atividade biológica do vWF, a ADAMTS13, que indiretamente pode afetar os níveis de vWF. Ademais, a intensidade da plaquetopenia durante o envenenamento de B. jararaca não depende da presença de vWF, e tendo em conta o caráter multifatorial do consumo plaquetário durante o envenenamento, sugerimos que outros mecanismos possam ser responsáveis pela plaquetopenia induzida pelo BjV. Com isso, concluímos que o consumo de vWF no envenenamento por B. jararaca é um fator contribuinte, porém não determinante, para as alterações da contagem plaquetária / Patients bitten by Bothrops snakes manifest a bleeding tendency in which thrombocytopenia is consistently observed. Systemic clinical manifestations, such as mucous bleeding and thrombotic microangiopathy in some patients, share similarities with symptoms of von Willebrand disease and thrombotic thrombocytopenic purpura. Some venom proteins - e.g. botrocetin (a C-type lectin-related protein) and snake venom metalloproteinases (SVMP) - disturbs, direct or indirectly, the interaction between platelets and von Willebrand factor (vWF) in vitro and in vivo, and may contribute thereby to snakebite-induced bleedings, once vWF is required for primary hemostasis. To better understand the relation between plasma vWF, and botrocetin and SVMPs from B. jararaca crude venom (BjV) in the thrombocytopenia induced by envenomation, we used two experimental models: Wistar heterogenic rats and vWF knockout mice (Vwf-/-). In the rat model, BjV was pre-incubated with saline (positive control), metalloproteinase inhibitor (Na2-EDTA), polyclonal anti-botrocetin antibodies, glycerol (antibody vehicle), or the combination of Na2-EDTA and anti-botrocetin antibodies; the negative control group was injected with saline only. After subcutaneous injection (s.c.) of treated venom (1.6 mg/kg), blood samples were collected after 3, 6 or 24 h, and platelet count, vWF antigen (vWF:Ag) and collagenbinding activity (vWF:CB), ADAMTS13 activity, vWF multimer distribution, and factor VIII (FVIII) coagulant activity were analyzed. To investigate the participation of vWF in thrombocytopenia, vWF knockout mice (Vwf-/-) and control mice (C57BL/6) were injected s.c. with saline only (negative control group) or BjV pre-incubated with saline (positive control group). The same protocols used for rats were accomplished in mice. Our results showed that all rats injected with any BjV treatment, including animals which received anti-botrocetin antibodies and/or Na2-EDTA-treated BjV, showed thrombocytopenia, with the nadir at 6h. vWF analysis exhibited a large individual variation among treatment groups, but there was a tendency to reduce vWF:Ag levels at 3 and 6 h in rats that received BjV pre-incubated with saline (without any inhibitor). Administration of BjV pre-incubated only with anti-botrocetin antibodies evoked a large reduction in vWF:Ag levels at 3 h, which returned to levels similar to those of the negative control group at 6 and 24 h. SVMP inhibition alone did not induce an important effect, but potentialized the activity of anti-botrocetin antibodies to inhibit the fall in both vWF:Ag and vWF:CB levels at 6 h. VWF multimer analysis had a large individual profile variation, although animals that received any BjV treatment tended to decrease the high and intermediate molecular weight multimers and to increase the low ones, especially at 24 h. FVIII showed diminished levels in all rats that received any BjV treatment at 3 and 6 h, without important variations among groups. Decreased levels of ADAMTS13 activity were noticed at 3 and 6 h, which were reverted by SVMP inhibition. In mice, thrombocytopenia was present in all control and knockout mice that received BjV, demonstrating independence of vWF presence. In control mice (C57BL/6), there were no relevant alterations in vWF:Ag during envenomation, although at 3 h there was a tendency to decrease it. Al together, our results showed that botrocetin present in crude venom does not affect thrombocytopenia induced by envenomation, but it changes the levels and function of plasma vWF. SVMP had a marked effect in ADAMTS13, the physiological enzyme that regulates vWF biological activity, which may affect vWF levels indirectly. In addition, thrombocytopenia during B. jararaca envenomation is independent of vWF, and considering the multifactorial features of platelet consumption during envenomation, we suggest that other mechanisms might account for BjV-induced thrombocytopenia. Therefore, we conclude that vWF consumption during B. jararaca envenomation is an ancillary mechanism, but not the main one to decrease platelet counts