Inhibition of the renin-angiotensin system does not reduce platelet activity at rest or during stress in hypertension.

OBJECTIVES: We investigated the influence of angiotensin receptor blockade and angiotensin-converting enzyme inhibition on stress-induced platelet activation in hypertensive patients. Secondary aims were effects on inflammation, coagulation, and endothelial function. METHODS: Following a 4-week placebo period, 25 hypertensive patients entered a double-blind, crossover study comparing enalapril (20 mg once daily) and losartan (100 mg once daily) treatment (each for 8 weeks). Patients were studied at rest and after a standardized exercise test. RESULTS: Mean arterial pressure was reduced from 119 ± 2 to 104 ± 2 (enalapril) and 106 ± 2 (losartan) mmHg (both P <0.001). Plasma angiotensin II decreased from 2.4 ± 0.4 to 0.5 ± 0.1 pmol/l with enalapril, and increased to 7.2 ± 1.3 pmol/l with losartan (both P <0.001). Exercise-evoked platelet activation, as evidenced by increased numbers of P-selectin-positive platelets (P <0.01), elevated circulating platelet-platelet aggregates (P <0.01) and soluble P-selectin levels (P <0.001), and increased platelet responsiveness to adenosine diphosphate and thrombin (both P <0.05). Neither drug influenced these markers of platelet activation at rest or following exercise. Markers of inflammation (high-sensitivity C reactive protein, interleukin-6, tissue necrosis factor-α), coagulation (tissue plasminogen activator antigen, prothrombin fragment F1+2), and endothelial function (von Willebrand factor, soluble vascular cellular adhesion molecule-1, and intercellular adhesion molecule-1) were also uninfluenced by treatment. CONCLUSION: Enalapril and losartan failed to reduce platelet activity both at rest and during exercise in hypertensive patients. Markers of inflammation, coagulation, and endothelial function were similarly unaffected. Inhibition of the renin-angiotensin system promotes its beneficial effects in hypertension through mechanisms other than platelet inhibition.

Cardiovascular effects in patrol officers are associated with fine particulate matter from brake wear and engine emissions

Background: Exposure to fine particulate matter air pollutants (PM2.5) affects heart rate variability parameters, and levels of serum proteins associated with inflammation, hemostasis and thrombosis. This study investigated sources potentially responsible for cardiovascular and hematological effects in highway patrol troopers. Results: Nine healthy young non-smoking male troopers working from 3 PM to midnight were studied on four consecutive days during their shift and the following night. Sources of in-vehicle PM2.5 were identified with variance-maximizing rotational principal factor analysis of PM2.5-components and associated pollutants. Two source models were calculated. Sources of in-vehicle PM2.5 identified were 1) crustal material, 2) wear of steel automotive components, 3) gasoline combustion, 4) speed-changing traffic with engine emissions and brake wear. In one model, sources 1 and 2 collapsed to a single source. Source factors scores were compared to cardiac and blood parameters measured ten and fifteen hours, respectively, after each shift. The "speed-change" factor was significantly associated with mean heart cycle length (MCL, +7% per standard deviation increase in the factor score), heart rate variability (+16%), supraventricular ectopic beats (+39%), % neutrophils (+7%), % lymphocytes (-10%), red blood cell volume MCV (+1%), von Willebrand Factor (+9%), blood urea nitrogen (+7%), and protein C (-11%). The "crustal" factor (but not the "collapsed" source) was associated with MCL (+3%) and serum uric acid concentrations (+5%). Controlling for potential confounders had little influence on the effect estimates. Conclusion: PM2.5 originating from speed-changing traffic modulates the autonomic control of the heart rhythm, increases the frequency of premature supraventricular beats and elicits proinflammatory and pro-thrombotic responses in healthy young men. [Authors]

Particulate matter exposure in cars is associated with cardiovascular effects in healthy young men

Exposure to fine airborne particulate matter (PM(2.5)) is associated with cardiovascular events and mortality in older and cardiac patients. Potential physiologic effects of in-vehicle, roadside, and ambient PM(2.5) were investigated in young, healthy, nonsmoking, male North Carolina Highway Patrol troopers. Nine troopers (age 23 to 30) were monitored on 4 successive days while working a 3 P.M. to midnight shift. Each patrol car was equipped with air-quality monitors. Blood was drawn 14 hours after each shift, and ambulatory monitors recorded the electrocardiogram throughout the shift and until the next morning. Data were analyzed using mixed models. In-vehicle PM(2.5) (average of 24 microg/m(3)) was associated with decreased lymphocytes (-11% per 10 microg/m(3)) and increased red blood cell indices (1% mean corpuscular volume), neutrophils (6%), C-reactive protein (32%), von Willebrand factor (12%), next-morning heart beat cycle length (6%), next-morning heart rate variability parameters, and ectopic beats throughout the recording (20%). Controlling for potential confounders had little impact on the effect estimates. The associations of these health endpoints with ambient and roadside PM(2.5) were smaller and less significant. The observations in these healthy young men suggest that in-vehicle exposure to PM(2.5) may cause pathophysiologic changes that involve inflammation, coagulation, and cardiac rhythm.

Hématome des muscles ilio-psoas: rappel des éléments diagnostiques

Introduction: La survenue d'une hémorragie dans les muscles iliopsoasconstitue une pathologie grave, dont le diagnostic est souventtardif et grevé d'une morbidité importante. Sa présentation cliniquedoit être reconnue précocement, en particulier par les médecins depremier recours.Cas clinique: Un patient de 65 ans est admis aux urgences en raisonde douleurs invalidantes de la jambe droite, prédominant sur la faceantérieure de la cuisse. Les douleurs irradient dans le pli inguinal, leflanc, la région lombaire, ainsi que la hanche droite. Elles sont associéesà une parésie du quadriceps droit. Le patient a bénéficié en2006 d'un remplacement de valve aortique, avec implantation d'unevalve mécanique motivant une anticoagulation par acenocoumarol.Il présente par ailleurs une parésie sur le territoire du nerf sciatiquedroit, après fracture du bassin en 1970. Le diagnostic est évoqué auvu d'une antioagulation supra-thérapeutique (INR 5).Un CT-scan de l'abdomen confirmera un important hématome(11 x 7 cm) du muscle iliaque droit (fig. 1) qui sera drainé chirurgicalement,après réversion partielle de la crase, permettant une évolutionfavorable.Discussion: Les hématomes des muscles ilio-psoas surviennentclassiquement de manière spontanée. Les symptômes sont peu spécifiques,à type de douleurs diffuses abdominales, lombaires ou crurales,de paresthésies, de limitation fonctionnelle ou de chute isoléede l'hémoglobine (Hb). Les patients sous anticoagulants (héparine,acenocoumarol) ou présentant des troubles de la coagulation (hémophilie,thrombopathie, maladie de von Willebrand) sont particulièrementà risque. Les complications sont fréquentes: compressions dunerf fémoral (avec hypoesthésie, parésie du quadriceps ou abolitiondu réflexe rotulien), anémie, état de choc. Le traitement implique lacorrection des troubles de la coagulation, ainsi qu'un suivi clinique,radiologique et biologique (Hb) régulier. Le traitement conservateurest proposé lors d'hématome de petite taille, si le patient est stable etpeu symptomatique. Dans les autres cas, un drainage chirurgical parvoie ouverte ou par voie percutanée est recommandé. L'embolisationartérielle s'affiche comme une future option thérapeutique.Conclusions: Ce cas illustre les différents éléments cliniques etbiologiques qui orientent précocement vers le diagnostic d'hématomedes muscles ilio-psoas. Il devrait favoriser l'évocation d'une pathologierare, permettant de garantir un diagnostic précoce.

Biomarkers of Host Response Predict Primary End-Point Radiological Pneumonia in Tanzanian Children with Clinical Pneumonia: A Prospective Cohort Study.

BACKGROUND: Diagnosing pediatric pneumonia is challenging in low-resource settings. The World Health Organization (WHO) has defined primary end-point radiological pneumonia for use in epidemiological and vaccine studies. However, radiography requires expertise and is often inaccessible. We hypothesized that plasma biomarkers of inflammation and endothelial activation may be useful surrogates for end-point pneumonia, and may provide insight into its biological significance. METHODS: We studied children with WHO-defined clinical pneumonia (n = 155) within a prospective cohort of 1,005 consecutive febrile children presenting to Tanzanian outpatient clinics. Based on x-ray findings, participants were categorized as primary end-point pneumonia (n = 30), other infiltrates (n = 31), or normal chest x-ray (n = 94). Plasma levels of 7 host response biomarkers at presentation were measured by ELISA. Associations between biomarker levels and radiological findings were assessed by Kruskal-Wallis test and multivariable logistic regression. Biomarker ability to predict radiological findings was evaluated using receiver operating characteristic curve analysis and Classification and Regression Tree analysis. RESULTS: Compared to children with normal x-ray, children with end-point pneumonia had significantly higher C-reactive protein, procalcitonin and Chitinase 3-like-1, while those with other infiltrates had elevated procalcitonin and von Willebrand Factor and decreased soluble Tie-2 and endoglin. Clinical variables were not predictive of radiological findings. Classification and Regression Tree analysis generated multi-marker models with improved performance over single markers for discriminating between groups. A model based on C-reactive protein and Chitinase 3-like-1 discriminated between end-point pneumonia and non-end-point pneumonia with 93.3% sensitivity (95% confidence interval 76.5-98.8), 80.8% specificity (72.6-87.1), positive likelihood ratio 4.9 (3.4-7.1), negative likelihood ratio 0.083 (0.022-0.32), and misclassification rate 0.20 (standard error 0.038). CONCLUSIONS: In Tanzanian children with WHO-defined clinical pneumonia, combinations of host biomarkers distinguished between end-point pneumonia, other infiltrates, and normal chest x-ray, whereas clinical variables did not. These findings generate pathophysiological hypotheses and may have potential research and clinical utility.

Om bräd-sågning

Invocatio: M.G.H.

Aspectos epidemiológicos e anatomopatológicos do hemagiossarcoma em cães: 40 casos (1965-2012)

Os aspectos epidemiológicos e anatomopatológicos de casos de hemangiossarcoma em cães da Região Central do RS foram estudados. Dos casos avaliados (n=40), cães idosos e da raça Pastor Alemão foram nitidamente os mais afetados (72,2% e 20% dos casos, respectivamente), visto que na população total de cães necropsiados nesse mesmo período (n=7.063) essa faixa etária e raça tiveram comparativamente uma prevalência bem mais baixa (14,6% e 10,1% dos casos, respectivamente). Na necropsia (n=40), os tumores ocorreram quase sempre como nódulos (92,5%) e, menos frequentemente, como massas (37,5%), e afetaram principalmente: baço (62,5%), pulmão (60%), fígado (52,5%), peritônio (42,5%), rim (37,5%), encéfalo (30%), pleura (25%) e coração (22,5%). Hemoperitônio (42,5%) e, consequentemente, anemia (22,5%) foram vistos com certa frequência. Na histologia (n=25), os hemangiossarcomas eram principalmente bem diferenciados (84%), de baixo grau (64%) e com estroma escasso (84%), mas frequentemente (68%) havia áreas com células demonstrando algum grau de atipia. Necrose, hemorragia e trombose foram vistos em todos os casos, mas hematopoiese extramedular (28%) e proliferação angiomatosa benigna (12%) foram achados menos comuns. Na imuno- -histoquímica (n=24), utilizando anticorpo anti-fator de von Willebrand, todos os casos demonstraram marcação de intensidade variável com um padrão citoplasmático finamente granular. Em relação à classificação anatômica, 55% dos hemangiossarcomas foram considerados como multicêntricos, 30% como primários com metástase(s) e 15% como solitários. Esse artigo discute esses resultados e propõe, com base em combinações de órgãos afetados, um esquema de separação entre hemangiossarcomas primário com metástase(s) e multicêntrico, a fim de tentar homogeneizar a maneira com que patologistas veterinários referem-se a esse neoplasma.

Intoxicação por selênio em suínos no Sul do Brasil

São descritos dois surtos de intoxicação por selênio em suínos na região Sul do Brasil. Foram acometidos leitões em fase de creche, entre 27 e 22 dias, com mortalidade variando de 16% a 15,3% (Surto 1 e 2 respectivamente). Os suínos apresentaram poliomielomalacia simétrica focal e lesões de casco, que inicialmente eram caracterizadas por uma linha avermelhada na borda coronária que evoluía nos suínos sobreviventes para desprendimento do casco. Os sinais clínicos iniciaram após seis dias (Surto 1) e 30 horas (Surto 2) da introdução da ração com alto teor de selênio. O surgimento dos sinais foi abrupto, caracterizado por andar cambaleante, com evolução para paralisia dos membros pélvicos e posteriormente tetraparesia. Macroscopicamente observaram-se focos circulares amarelados com áreas deprimidas mais escuras, restritas ao corno ventral da substância cinzenta em intumescências cervical e lombar. Microscopicamente essas áreas corresponderam à malacia da substância cinzenta, caracterizada por microcavitações, perda neuronal, cromatólise, neuronofagia, infiltrado de células Gitter, microgliose, astrócitos de Alzheimer tipo II e proliferação de células endoteliais evidenciadas na imunohistoquímica (IHQ) para fator de von Willebrand. Ainda, no segundo surto, dois animais apresentaram vacuolização difusa do citoplasma de neurônios e em um suíno foram observados astrócitos gemistocíticos. Na IHQ para GFAP ficou evidenciada uma astrocitose e astrogliose. Além dessas alterações medulares, em dois suínos observou-se, polioencefalomalácia simétrica no tronco encefálico. Em amostras de ração, detectou-se 3,38ppm (Surto 1) e 154ppm (Surto 2) de Se/kg e em amostras de fígado foram encontradas dosagens superiores a 3,34ppm (variando de 3,34 até 10ppm). No Surto 2, após 44 dias da retirada da ração, foi realizada eutanásia de seis suínos para monitoramento de níveis hepáticos de selênio (dois suínos controles e quatro sobreviventes ao surto) e todos apresentaram níveis normais de selênio no fígado.

Retrospective canine skin peripheral nerve sheath tumors data with emphasis on histologic, immunohistochemical and prognostic factors

Abstract: In this retrospective study was determined the frequency of canine skin peripheral nerve sheath tumors (PNST) in cases diagnosed by the Setor de Patologia Veterinária of the Universidade Federal do Rio Grande do Sul (SPV-UFRGS), Brazil, between the years 2000 and 2012. The canine profiles, as well as histological, immunohistochemical and prognostic aspects of the tumors were based on 70 samples, comprising 40 females, 29 males and one unspecified sample. Between 2000 and 2012, 2,984 skin tumors of dogs were diagnosed in the SPV-UFRGS, totaling 2.34% of skin neoplasms in dogs. Animals that comprised the largest amount of samples (43%) were those with no breed (SRD), followed by German Shepherds (10%). Females were more affected than males (40/70 - 57% and 29/70 - 41% respectively). Skin PNST of this research showed predominant localization on the limbs (40% in the forelimbs and 29% in the hindlimbs); affecting adult dogs, mostly aged between 8 and 11 years (54%). The samples were routinely processed for hematoxylin and eosin, and were also evaluated by toluidine blue and Masson's trichrome staining, and immunohistochemistry (IHC) anti-vimentin, -S-100, -GFAP, -actin, von Willebrand factor and neurofilament. Anisocytosis and anisokaryosis, mitotic index, intratumoral necrosis, invasion of adjacent tissues, tumor location, local recurrence and metastasis were related to the diagnosis of benign (49/70) or malignant tumor (21/70). The Antoni A histological pattern was observed more frequently in benign tumors. The immunohistochemistry helped to diagnose PNST, and anti-vimentin and anti-protein S-100 showed the highest rates of immunostaining. Throughout statistical analysis of animals with tumor recurrence, it was found that the chance of an animal with a malignant peripheral nerve sheath tumor to develop recurrence is 4.61 times higher than in an animal that had a benign tumor.

De Philota, Parmenionis filio

Invokaatio: D.D.

De expeditione Johannis I:mi

Dedikaatio: Ernst. Gust. von Willebrand.

Microangiopatias trombóticas: púrpura trombocitopênica trombótica e síndrome hemolítico-urêmica

As microangiopatias trombóticas (MATs) são condições caracterizadas por oclusão microvascular generalizada por trombos de plaquetas, trombocitopenia, e anemia hemolítica microangiopática. Duas manifestações fenotípicas típicas das MATs são a síndrome hemolítica urêmica (SHU) e a púrpura trombocitopênica trombótica (PTT). Outras doenças ocasionalmente apresentam manifestações similares. Na dependência de prevalecer a lesão renal ou a cerebral, duas entidades patologicamente indistinguíveis, mas de alguma forma clinicamente diferentes, têm sido descritas: a SHU e a PTT. Injúria das células endoteliais é o fator desencadeante central na sequência de eventos que levam a MAT. Perda da trombo resistência fisiológica, adesão de leucócitos no endotélio lesado, consumo de complemento, liberação e fragmentação anormais do fator de von Willebrand (FvW), e aumento do estresse de cisalhamento vascular podem sustentar e ampliar o processo microangiopático. Anormalidades intrínsecas do sistema do complemento e do FvW podem acompanhar a predisposição genética à doença, que pode ter um papel chave, em particular nas formas recorrentes e familiares. Nos casos de SHU associada à diarreia (SHU+D), o dano endotelial renal é mediado (pelo menos em parte) pela Shigatoxina (Stx) bacteriana, uma família de toxinas elaboradas por certas cepas da Escherichia coli e Shigella dysenteriae. A evolução é geralmente boa na criança, na SHU associada a Stx, enquanto sequelas renais e neurológicas são mais frequentemente encontradas em adultos, formas familiares e atípicas da SHU e na PTT. Estudos recentes têm demonstrado que a deficiência na clivagem do FvW pela proteinase ADAMTS13 pode ser genética ou mais comumente adquirida, resultante da produção de anticorpos inibidores da ADAMTS13, causando a PTT. Durante a última década, demonstrou-se que a SHU atípica (SHU-D) é uma doença de desregulação da via alternativa do complemento. Uma série de mutações e polimorfismo em genes que codificam proteínas reguladoras do complemento sozinhas ou em combinação podem levar a SHU atípica. Aproximadamente 60% dos casos de SHU atípica têm mutações do tipo "perda da função" em genes que codificam as proteínas reguladoras do complemento, as quais protegem as células hospedeiras da ativação do complemento: fator H do complemento (FHC), fator I (FIC) e proteína cofator de membrana (PCM ou CD46), ou mutações do tipo "ganho da função" em genes que codificam o FHC ou C3. Além disso, aproximadamente 10% dos pacientes com SHU atípica têm deficiência na função do FHC devido a anticorpos anti-FHC. Mesmo que as MATs sejam condições altamente heterogêneas, um terço dos pacientes tem deficiência severa da ADA-MTS13. Transfusões de plaquetas são contraindicadas nesses pacientes. Infusão de plasma ou plasma exchange (PE) é o único tratamento eficiente.

Platelet adhesion signalling and the regulation of thrombus formation

Platelets perform a central role in haemostasis and thrombosis. They adhere to subendothelial collagens exposed at sites of blood vessel injury via the glycoprotein (GP) 1b-V-IX receptor complex, GPV1 and integrin alpha(2)beta(1)-These receptors perform distinct functions in the regulation of cell signalling involving non-receptor tyrosine kinases (e.g. Src, Fyn, Lyn, Syk and Btk), adaptor proteins, phospholipase C and lipid kinases such as phosphoinositide 3-kinase. They are also coupled to an increase in cytosolic calcium levels and protein kinase C activation, leading to the secretion of paracrine/autocrine platelet factors and an increase in integrin receptor affinities. Through the binding of plasma fibrinogen and von Willebrand Factor to integrin alphaIIbbeta(3), a platelet thrombus is formed. Although increasing evidence indicates that each of the adhesion receptors GPIb-V-IX and GPV1 and integrins alpha(2)beta(1) and alpha(IIb)beta(3) contribute to the signalling that regulates this process, the individual roles of each are only beginning to be dissected. By contrast, adhesion receptor signalling through platelet endothelial cell adhesion molecule 1 (PECAM-1) is implicated in the inhibition of platelet function and thrombus formation in the healthy circulation. Recent studies indicate that understanding of platelet adhesion signalling mechanisms might enable the development of new strategies to treat and prevent thrombosis.

The antithrombotic effect of dextran-40 in man is due to enhanced fibrinolysis in vivo

BACKGROUND: Dextran-40 is effective in reducing postoperative Doppler-detectable embolization in patients undergoing carotid endarterectomy (CEA). Dextrans are thought to have antithrombotic and antiplatelet effects. The mode of action is unclear. In rats, dextran blocks uptake of tissue plasminogen activator (tPA) by mannose-binding receptors. Because this would have the effect of enhancing endogenous fibrinolysis, we explored this effect of dextran-40 on fibrinolysis in man. METHODS: Twenty patients undergoing endovascular stenting for abdominal aortic aneurysm were randomized to receive 100 mL of 10% dextran-40 or saline, over 1 hour, during their operation in addition to heparin. Blood samples were taken preoperatively, intraoperatively (immediately after operative procedure), and 24 hours postoperatively. Thrombi were formed in a Chandler loop and used to assess endogenous fibrinolysis over 24 hours, measured as the fall in thrombus weight, and the release of fluorescently labelled fibrinogen from the thrombus. Plasma samples were analyzed for markers of fibrinolysis; plasmin-antiplasmin (PAP), PAI-1, and t-PA, and for functional von Willebrand factor (vWF). Platelet response to thrombin and other agonists was measured by flow cytometry. RESULTS: Thrombi formed ex vivo from the intraoperative blood samples from the dextran-treated patients exhibited significantly greater fibrinolysis vs preoperative samples, seen both as a significantly greater percentage reduction in thrombus weight (from 34.7% to 70.6% reduction) and as an 175% increase in the release of fluorescence (P < .05). Fibrinolysis returned to baseline levels the next day. No change was seen in the saline-treated group. Plasma levels of PAP and PAI-1 increased significantly postoperatively in the dextran-treated group vs the saline group (P < .05). The postoperative level of functional VWF was significantly lower in the dextran-treated group vs controls. A specific reduction occurred in the platelet response to thrombin, but not to other agonists, in the intraoperative samples from the dextran-treated group (11.1% vs 37.1%; P = .022), which was not seen in the controls. CONCLUSIONS: These data are consistent with a rise in plasmin due to dextran blockade of tPA uptake in vivo, leading to enhanced fibrinolysis, cleavage of vWF and of the platelet protease-activated receptor-1 (PAR-1) thrombin receptor. This suggests that dextran exerts a combined therapeutic effect, enhancing endogenous fibrinolysis, whilst also reducing platelet adhesion to vWF and platelet activation by thrombin. The proven antithrombotic efficacy of low-dose dextran in carotid surgery may be applicable to wider therapeutic use.

A novel interaction between FlnA and Syk regulates platelet ITAM-mediated receptor signaling and function

Filamin A (FlnA) cross-links actin filaments and connects the Von Willebrand factor receptor GPIb-IX-V to the underlying cytoskeleton in platelets. Because FlnA deficiency is embryonic lethal, mice lacking FlnA in platelets were generated by breeding FlnA(loxP/loxP) females with GATA1-Cre males. FlnA(loxP/y) GATA1-Cre males have a macrothrombocytopenia and increased tail bleeding times. FlnA-null platelets have decreased expression and altered surface distribution of GPIbalpha because they lack the normal cytoskeletal linkage of GPIbalpha to underlying actin filaments. This results in approximately 70% less platelet coverage on collagen-coated surfaces at shear rates of 1,500/s, compared with wild-type platelets. Unexpectedly, however, immunoreceptor tyrosine-based activation motif (ITAM)- and ITAM-like-mediated signals are severely compromised in FlnA-null platelets. FlnA-null platelets fail to spread and have decreased alpha-granule secretion, integrin alphaIIbbeta3 activation, and protein tyrosine phosphorylation, particularly that of the protein tyrosine kinase Syk and phospholipase C-gamma2, in response to stimulation through the collagen receptor GPVI and the C-type lectin-like receptor 2. This signaling defect was traced to the loss of a novel FlnA-Syk interaction, as Syk binds to FlnA at immunoglobulin-like repeat 5. Our findings reveal that the interaction between FlnA and Syk regulates ITAM- and ITAM-like-containing receptor signaling and platelet function.