Therapeutics and COVID-19: living guideline - 16 September 2022

The WHO Therapeutics and COVID-19: living guideline contains the Organization's most up-to-date recommendations for the use of therapeutics in the treatment of COVID-19. The latest version of this living guideline is available in pdf format (via the 'Download' button) and via an online platform, and is updated regularly as new evidence emerges. This twelfth version of the WHO living guideline now contains 19 recommendations. This latest update provides updated recommendations for remdesivir, addresses the use of combination therapy with corticosteroids, interleukin-6 (IL-6) receptor blockers and Janus kinase (JAK) inhibitors in patients with severe or critical COVID-19, and modifies previous recommendations for the neutralizing monoclonal antibodies sotrovimab and casirivimab-imdevimab in patients with non-severe COVID-19.

Plasma de convaleciente para el tratamiento de la COVID-19: Protocolo para el acceso y uso en Venezuela / Convalescent Plasma for the Treatment of COVID-19: Protocol for access and use in Venezuela

En diciembre 2019, en Wuhan, China, se registró un aumento inusual de casos de infección respiratoria aguda de rápida progresión y alta letalidad. Al poco tiempo es identificado el agente causal, un coronavirus denominado SARS-CoV-2 y se caracteriza una nueva enfermedad, COVID-19. En ausencia hasta el momento de tratamientos específicos, eficaces y seguros, se justifica explorar alternativas científicamente fundamentadas a nuestro alcance como el uso de Plasma de Convaleciente (PC-CoV19) como coadyuvante para el tratamiento de la COVID-19. El plasma de pacientes recuperados de una enfermedad infecciosa, Plasma de Convaleciente, ha sido utilizado en el tratamiento de patologías infecciosas. Hay antecedentes inmediatos de su uso en enfermedades producidas por otro tipo de coronavirus y se registran experiencias y estudios clínicos con resultados preliminares durante esta pandemia. Quimbiotec, empresa productora de hemoderivados y fármacos recombinantes del Estado venezolano, y el Banco Municipal de Sangre, definen un protocolo para promover condiciones para la aféresis, procesamiento, conservación, almacenamiento, distribución, transfusión y evaluación de la seguridad y eficacia del PC-CoV19 como alternativa en el tratamiento de la COVID-19 en Venezuela. Se incluye la identificación de capacidades y de talento, la estructura física, equipos y especialistas necesarios, así como la definición de procesos para establecer rutinas controladas y auditables para sentar bases del acceso y uso del PC-CoV19 en el Sistema Nacional de Salud de Venezuela y preparar el diseño y ejecución de estudios clínicos. Se presenta el Protocolo y algunos nudos críticos en su ejecución a la fecha, herramientas y estrategias utilizadas para su solución(AU)

On December 2019, in Wuhan, China, there was an unusual increase in cases of a fast-progressing acute respiratory infection with high fatality rate. Soon after, the causing agent is identiied, a coronavirus called SARS-CoV-2, and a new disease, COVID-19 is characterized. Currently, in the absence of specific, effective and safe treatments, it is justified to explore all scientifically based alternatives available to us, such as the use of Convalescent Plasma (PC-CoV19) as acoadjutant treatment of COVID-19.Plasma from patients who have recovered from an infectious disease, Convalescent Plasma, has been used in the treatment of other infectious disease. There is recent history of its use in diseases caused by another type of coronavirus, and clinical experiences and studies have already been published with preliminary results during this pandemic. Quimbiotec, a Venezuelan State public company that produces blood products and recombinant drugs, and Banco Municipal de Sangre, deined a protocol to promote conditions for aphaeresis, processing, conservation, storage, distribution, transfusion, and evaluation of safety and eficacy of PC-CoV19 as an alternative for the treatment of COVID-19 in Venezuela. This protocol includes identification of capacities, physical structure, equipment and skills, talent, professionals needed, as well as a definition of processes to establish controlled and auditable routines to lay the foundations for access and use of PC-CoV19 in the Venezuela Health System, and prepare the design and implementation of clinical studies. The protocol and currently critical points in its implementation, as well as tools and strategies used for its solution, are presented(AU)

Consideraciones regulatorias sobre la autorización del uso de plasma de convalecientes (PC) para atender la emergencia de COVID-19, 22 de abril de 2020 / Regulatory considerations on the authorization of the use of convalescent plasma (PC) to treat the COVID-19 emergency, April 22, 2020

La inmunización pasiva se ha utilizado para la prevención y el tratamiento de algunas enfermedades infecciosas humanas desde el siglo pasado. El plasma inmune obtenido de personas curadas o recuperadas fue el tratamiento de elección en casos de fiebre hemorrágica argentina. Además, fue utilizado en los brotes de ébola en África, y los brotes de SARS y MERS donde se pusieron en práctica protocolos de tratamiento similares, considerando que en el momento no existían otras alternativas terapéuticas. A la fecha, la experiencia con el uso de plasma de convalecientes para tratamiento de la COVID-19 es limitada pero los resultados preliminares indican una potencial utilidad. Diversos estudios clínicos controlados se encuentran en marcha, lo que permitirá recolectar mayor evidencia científica de calidad para confirmar la eficacia y seguridad de esta intervención. En este escenario, las recomendaciones prevén su uso bajo condiciones experimentales en el marco de la regulación de cada país. Por otro lado, se plantea el reto de la recolección, procesamiento y distribución de plasma de pacientes convalecientes en amplia escala para responder a las eventuales necesidades clínicas. Al respecto se han publicado diferentes orientaciones para la colecta y uso de plasma de pacientes convalecientes en enfermedades infecciosas, como en el brote de ébola e incluso para la actual situación de la COVID-19.

Effect of fresh frozen plasma on the in vitro activation of U937 monocytes: a potential role for the age of blood donors and their underlying cytokine profile

BACKGROUND: Fresh frozen plasma (FFP) administration may increase the risk of nosocomial infections in parallel with the development of immune modulation. This could be driven by soluble mediators, possibly influencing the in vitro activation of human U937 monocyte cells, in a manner dependent on the age of the donors. METHODS: FFP donors were stratified into groups of 19-30 years, 31-40 years or 41-50 years, and U937 cells were cultured with FFP (alone or plus lipopolysaccharide-LPS) for 24 h. Both in FFP and supernatants, TNF, IL-1ß, IL-6, and IL-10 levels were measured by ELISA. Additionally, CD11B, TLR2, and CASP3 gene expression were measured by qtPCR in U937 cells. Total phagocytic activity was also assayed. RESULTS: Elevated IL-10, but low TNF and IL-1ß levels were measured in FFP from individuals aged 19-40 years, whereas in individuals aged 41-50 years FFP were characterized by equalized TNF and IL-10 levels. Elevated IL-6 levels were found in all FFP samples, especially in those from the oldest individuals. FFP stimulation was associated with striking modifications in cytokine production in an age-dependent way. Exposure to FFP attenuates the response to LPS. TLR2 and CD11B expression were enhanced regardless of the age of plasma donors, although CASP3 expression was increased only when FFP from individuals aged 19-40 years were tested. Phagocytosis decreased after exposure to FFP regardless of donor age. CONCLUSION: Our results suggest that soluble mediators in FFP may modulate the functioning of monocytes. Interestingly, this effect appears to be partially influenced by the age of donors.

Antivenenos ofídicos: comparación del desempeño de dos métodos de obtención / Snake Antivenoms: Performance Comparison of Two Preparation Methods

INTRODUCCIÓN: Los sueros antiofídicos pueden prepararse por precipitación de suero o plasma equino hiperinmune con sulfato de amonio o con ácido caprílico. OBJETIVO:Comparar el rendimiento de ambos métodos. MATERIALES Y MÉTODOS: Las inmunoglobulinas se precipitaron con sulfato de amonio, y la albúmina con ácido caprílico. El nivel de anticuerpos en la preparación final se midió por el método de ELISA. RESULTADOS: El ácido caprílico al 3...

INTRODUCTION: Antivenom sera can be prepared by precipitation of hyperimmune equine serum or plasma with ammonium sulfate or caprylic acid. OBJECTIVE:To compare the performance of both methods. METHODS:The immunoglobulins were precipitated with ammonium sulfate, and the albumin with caprylic acid. The antibody level in the final preparation was measured by ELISA. RESULTS: The 3...

Efeito de dietas contendo plasma sanguíneo desidratado sobre características microbiológicas, imunológicas e histológicas de leitões leves ao desmame / Effect of spray-dried plasma diets on microbiological, immunological and histological parameters of light weight weaned pigs

Foram avaliados os efeitos do plasma sanguíneo desidratado (PSD) sobre desempenho, perfil imunológico, histológico, microbiológico e peso de órgãos de leitões leves, desmamados aos 21 dias de idade. Foram utilizados 24 leitões, com idade média inicial de 21 dias, em delineamento experimental completamente ao acaso. Os tratamentos foram: T1 - animais pesados ao desmame, sem suplementação com PSD; T2 - animais leves ao desmame, suplementados com 10g/animal/dia de PSD; T3 - animais leves ao desmame, suplementados com 20g/animal/dia de PSD; T4 - animais leves ao desmame, sem suplementação com PSD. A adição de 20g de PSD na dieta melhorou o ganho diário de peso, aumentou o peso (g/kg) do baço e o título de IgA no soro entre 21 e 31 dias de idade. A inclusão de 10g de PSD aumentou o comprimento e a largura do linfonodo ileocólico. A inclusão de PSD traz benefícios aos leitões nos primeiros 10 dias pós-desmame, atuando principalmente nos órgãos linfoides e na mucosa intestinal.

The aim of this experiment was to evaluate the effects of spray-dried plasma (SDP) on the growth performance, immunological, histological and microbiological profile and weight of organs of light weight weaned pigs. The trial was done using 24 pigs with an initial mean age of 21 days in a completely randomized experimental design. The treatments were: T1 - heavy weight weaned pigs, without SDP supplementation; T2 - light weight weaned pigs, supplemented with 10g/animal/day of SDP; T3 - light weight weaned pigs, supplemented with 20g/animal/day of SDP; T4 - light weight weaned pigs, without SDP supplementation. The inclusion of 20g of SDP in the diet improved the weight gain, spleen weight (g/kg) and serum IgA title between 21 and 31 days of age. The inclusion of 10g of SDP in the diet improved the length and width of the ileocolic lymph node. In the first 10 days after weaning, SDP improved the development of lymphoid organs and the protection of the intestinal mucosa.

Proteínas séricas de potros da raça Puro Sangue Árabe recém-desmamados ou com mais de trinta dias de desmame / Serum protein profile in Arabian foals recently weaned or at more than thirty days after weaning

A fase perinatal do desenvolvimento constitui um dos períodos de vida mais desafiadores para o sistema imunológico dos potros. O objetivo do presente estudo foi verificar o perfil protéico sérico de parâmetros relacionados à imunidade de equinos jovens no período perinatal, verificando-se a transferência de imunidade passiva. Oito animais desmamados há um dia, formaram o Grupo 1 (G1), enquanto vinte animais desmamados há mais de trinta dias formaram o Grupo 2 (G2). A concentração sérica de proteína total foi determinada por refratometria. Para o fracionamento das proteínas, utilizou-se eletroforese em gel de acrilamida. Os resultados obtidos foram submetidos à análise de medidas repetidas e ao teste Tukey (p<0,05) para comparação das médias. As concentrações de IgA apresentaram diferença (p<0,05) entre os grupos, porém os valores observados encontravam-se dentro do considerado normal para equinos adultos. Não houve diferença (p>0,05) nas concentrações de IgG. O estabelecimento adequado da imunidade celular ocorre durante a fase neonatal, nos animais que ingerem adequadamente o colostro e o leite. O presente estudo determinou diferenças no perfil protéico sérico de parâmetros relacionados à imunidade de equinos jovens no período imediato ao desmame, comparados com animais desmamados há mais de 30 dias. De acordo com os valores observados, concluiu-se que os animais, mesmo desmamados precocemente, obtiveram transferência adequada de imunidade passiva.

The perinatal phase of foal development is one of the most challenger period for the immune system. The present study has analyzed serum protein profile, considering variables related to immunity in foals at the perinatal phase, verifying passive immunity transfer. The group 1 (G1) contained eight foals evaluated one day after weaning, and group 2 (G2) included twenty foals at more than thirty days after weaning. Total protein concentration was determined by means of refractometry. The concentration of serum proteins was determined through sodium dodecyl sulphatepolyacrylamide gel electrophoresis. Results were submitted to analysis of variance and Tukey test (P<0.05). IgA concentration showed difference (P<0.05) between the two studied groups, however data were within adult healthy horses normal values. IgG didn't show statistical difference (P>0.05). The cellular immunity establishment occurs in the neonatal phase, in foals that suckled colostrum and milk properly. The present study showed differences in serum protein profile, considering variables related to immunity, in foals immediately after weaning comparing to foals at more than 30 days after weaning. According to the observed values, we conclude that foals, even early weaned, showed proper passive immunity tranfer.

Hemocomponentes en la hemorragia obstétrica mayor / Blood components in major obstetric hemorrhage

INTRODUCCIÓN: La hemorragia obstétrica mayor constituye una complicación obstétrica donde ocurre una pérdida de 1000 (mL) o más de sangre después de terminada la tercera etapa del trabajo de parto. OBJETIVO: Determinar el uso de los hemocomponentes en la Hemorragia Obstétrica Mayor en el Servicio de Transfusiones del Hospital Ginecobstétrico Eusebio Hernández. Relacionar las principales reacciones postransfusionales inmunológicas y no inmunológicas que aparecen en estas pacientes. MÉTODOS: Se realizó un estudio retrospectivo en 109 puérperas que presentaron hemorragia obstétrica mayor y requirieron del uso de hemocomponentes en el periodo comprendido entre enero del 2006 y septiembre del 2008. RESULTADOS: De 8 987 puérperas, 109 presentaron esta complicación obstétrica lo que representó el 1,13 por ciento. En el año 2007 ocurrieron el mayor número de casos. Llama la atención que las 109 pacientes recibieron concentrado de eritrocitos y que se transfundieron 2,66 unidades de este hemocomponentes por pacientes. El 100 por ciento de los casos tuvieron requerimientos transfusionales y el 1,83 por ciento de los casos presentaron reacciones postransfusionales. Los principales hemocomponentes empleados fueron los concentrados de eritrocitos y plasma fresco congelado. Todas las pacientes se consideraron poli transfundidas al recibir más de una unidad de concentrado de eritrocitos para su tratamiento. CONCLUSIONES: Profundizar en el comportamiento de los parámetros hematológicos antes y después del uso de los hemocomponentes en estas pacientes, para evaluar precozmente la aparición de trombocitopenia dilucional, el consumo de factores plasmáticos de la coagulación o la aparición de la coagulación intravascular diseminada

INTRODUCTION: Major obstetric hemorrhage is a complication where occur a loss of 1000 (mL) or more of blood after termination the third stage of labor. OBJECTIVE: To determine the use of hemocomponents in the major obstetric hemorrhage in the Transfusions Service of the Eusebio Hernández Gynecology and Obstetrics Hospital. To relate he major immunological and non-immunological post-transfusion reactions present in these patients. METHODS: A retrospective study was conducted in 109 puerperal patients presenting with major obstetric hemorrhage requiring the use of hemo-components from January, 2006 to September, 2008. RESULTS: From 8 987 puerperal patients, 109 had this obstetric complication accounting for the 1.13 percent. In 2007, there was the highest figure of cases. Interestingly, the 109 patients received erythrocytes concentrates transfusing 2.66 units of these hemo-components by patient. The 100 percent of cases had needs of transfusions and the 1.83 percent had post-transfusion reactions. The main hemo-components used were the erythrocyte concentrates and freeze fresh plasma. All patients were considered poli-transfused at receive more than one unit of above mentioned concentrate for their treatment. CONCLUSIONS: To deepen in behavior of hematological parameters before and after use of hemo-components in these patients to assess early the appearance of dilution thrombocytopenia, the consumption of coagulation plasma factors or the appearance of the disseminated intravascular coagulation

Comparison between sensitivity of autologous skin serum test and autologous plasma skin test in patients with chronic idiopathic urticaria for detection of antibody against IgE or IgE receptor [FcepsilonRIalpha]

Intradermal injection of autologous serum and plasma elicit a cutaneous reactivity in almost 45-60% of patients with Chronic Idiopathic Urticaria [CIU]. This reactivity is associated with the presence of auto antibodies against IgE or IgE receptors. This study was carried out to compare the cutaneous reactivity of autologous serum and plasma skin tests in a series of patients with CIU for diagnosis of auto antibodies against IgE or IgE receptor. Fifty eight patients with CIU were injected intradermally with autologous serum and plasma [anticoagulated by citrate]. Histamine was used as positive control and normal saline as negative control. The study group was checked by routine laboratory tests [CBC, U/A etc], allergens with skin prick tests, and serum IgE level, and auto antibodies against thyroid as well. Duration of urticaria was another factor which was assessed. There was no significant difference between positive ASST and positive APST patients for the above mentioned tests. 77.6% of the patients were Positive for APST and 65.5% were ASST positive. Duration of urticaria was longer in patients with positive ASST and APST than ASST and APST negative patients, although the difference was not statistically significant. Autologous serum skin test [ASST] and autologous plasma skin test [APST] could be used for estimation of duration and severity of urticaria and planning for the treatment

Immunogenicity of plasma-derived hepatitis B vaccine in preterm infants.

The objective was to determine whether plasma-derived hepatitis B vaccine is immunogenic in preterm appropriate for gestation babies when administered at birth and to compare the immunogenicity between 5 micrograms and 10 micrograms doses of the vaccine in these babies. Fifty preterm neonates (31-36 weeks gestation) were randomized to receive 5 micrograms or 10 micrograms doses of plasma-derived hepatitis B vaccine at birth, with subsequent doses 1 and 6 months later. Serum specimens were obtained a month after each dose of the vaccine and were tested for antibody to hepatitis B surface antigen (anti-HBs). Thirty six babies (gestation 31-36 weeks), 18 from each group competed the study. While 89.2% of the babies seroconverted, 82.1% achieved seroprotective titres of anti-HBS (> 10 mIU/ml). There was no difference between weight, gestational age, age of administration of vaccine and age of estimation of anti-HBs between 5 micrograms and 10 micrograms groups. The difference in the seroprotective rates were not statistically different between the groups (5 micrograms 78.5%; 10 micrograms--85.7%). Although immune response to plasma derived hepatitis B vaccine in preterm babies is suboptimal when the first dose is administered at birth, the full course achieves adequate seroprotective levels.

Distress respiratorio agudo postransfusional en un caso de cirugía pediátrica craneofacial / Postransfusional acute respiratory distress in a case of craniofacial pediatric surgery

Se describe el caso de un Distress Respiratorio Agudo postoperatorio transfusional en una niña de 5 años intervenida de Hipertelorismo congénito. Durante la cirugía, sangrado profuso por lesión de Seno Longitudinal Superior, que exigió una reposición total de 6 litros con transfusión masiva. Al final del procedimiento se evidencia coagulopatía que se corrige con plasma fresco, crioprecipitado y plaquetas. La paciente, estable y extubada, cursa su postoperatorio en Centro de Tratamiento Intensivo. En el postoperatorio inmediato, post transfusión de 400 ml. de sangre, instala Edema Agudo de Pulmón, con hemodinamia estable y PVC 5 cm H2O. La evolución mostró PaO2 de menos de 100 con mejoría al 3§ y 4§ día. Estando aún en Asistencia Mecánica Respiratoria con parámetros de extubación, al cuarto día se realiza otra transfusión de sangre total instalando nuevamente importante insuficiencia respiratoria con Edema Agudo de Pulmón. Las diferentes etiologías de Edema Agudo de Pulmón postoperatorio post shock, neurológico, aspirativo, hipervolémico y/o cardiogénico fueron descartados en la evolución. El diagnóstico definitivo fue el de Distress Respiratorio agudo postransfusional. En la etiología del mismo se plantea un mecanismo de tipo inmunológico por transferencia pasiva de anticuerpos antileucocitarios del dador al receptor. La evolución fue hacia la mejoría lográndose la extubación al 9§ día. El control a los 4 meses fue normal.

Inhibition of hematopoiesis by a plasma factor in a case of aplastic anemia associated with systemic lupus erythematosus

Systemic Lupus Erythematosus (SLE) may be associated with inhibition of hematopoiesis mediated by antibodies, T-cells or both. A 41-year-old woman with a five-year history of SLE treated with prednisone was admitted to Cabrini Medical Center in New York. The patient complained of fever, chills, arthralgias, general malaise, weakness and dyspnea on exertion, and showed malar rash, pallor, and a systolic ejection murmur along the left sternal border. Admission work up included a CBC with evidence of moderate pancytopenia, a normal EKG, and a normal chest X-ray. The patient's anemia was symptomatic and required a transfusion of packed red blood cells (PRBC's). Bone marrow biopsy and aspiration revealed an aplastic marrow with few hypoplastic islands of hematopoietic elements. The patient was treated with plasmapheresis, achieving immediate progress towards recovery. Bone marrow culture studies (erythroid BFU-E, and myeloid CFU-GM) were done by incubating various titers of the patient's acute phase plasma with normal bone marrow cells. This was done to determine if the patient's plasma contained any hematopoietic inhibitory activity, as has been reported in other cases. Our experiments demonstrated marked inhibition of erymathropoiesis and myelopoiesis in vitro, when various titers of the patient's plasma were included in the culture media. Control plasma produced no inhibition. These studies support the hypothesis that a circulating antibody which inhibits hematopoiesis may be produced in SLE patients with aplastic anemia, and be responsible for it

Utilización de pools de suero o de saliva, en la determinación de anticuerpos al VIH-1/2 por técnicas rápidas y convencionales de E.L.I.S.A / Utilization of serum or saliva pools in determination of VIH-1/2 amtibodies for rapid and conventional technic of E.L.I.S.A.

Con objeto de evaluar la utilidad del empleo de muestas combinadas (pools) de suero 'o de saliva en el diagnóstico de la infección con los virus de la Inmunodeficiencia Humana, se estudiaron 500 personas, 100 infectadas con el V.I.H.-1 y 400 clínicamente sanas. A todas ellas se les tomaron simultáneamente muestras de sangre y de saliva. Se formaron 100 pools de muestras de sangre, y 100 pools de saliva, mezclando 200 microlitros ya fuera de suero o de saliva de una persona seropositiva y 4 seronegativas. Cada muestra individual y cada pool se analizaron con las técnicas de E.L.I.S.A. convencional y rápida (Abbott HIV-1/HIV-2 EIA y TEST PACK). Todas las muestras repetidamente positivas se confirmaron con la técnica de Western Blot (Cambridge Biotech HIV). Cada pool tanto de suero como de saliva fue estudiado de la misma manera. Los resultados obtenidos mostraron un 100 por ciento de correlación tanto en las muestras consideradas inidividualmente como en las combinadas; la especificidad, sensibilidad y valor predictivo no se vieron afectadas con el empleo de muestas combinadas (pools) ya fueran de suero o de saliva.

Glycosphingolipids of porcine blood: human blood group A and H antigens with type 1 chain in erythrocytes and plasma.

Glycosphingolipids were purified from porcine erythrocytes and plasma. Two minor glycolipids with human blood group A and H antigenicities were found in both sources as components. The two antigenic glycolipids were identified as a hexaglycosylceramide (IV3 alpha GalNAc,IV2 alpha Fuc-Lc4Cer) for the A antigen and pentaglycosylceramide (IV2 alpha Fuc-Lc4Cer) for the H antigen and belonged to lactoseries (type 1 sugar chain) in contrast to those with neolacto core (type 2 sugar chain) in human erythrocytes, thereby endorsing biochemically the previous serological observations that the A antigen on porcine erythrocytes is uptake from plasma, probably the H antigen being the case. In addition to major glycolipids of globoseries in red cells and plasma, a variety of acidic glycolipids including two classes of sulphatides (sulphated galactosylceramide and sulphated lactosylceramide) and five classes of gangliosides (GM3, GD3, GM1, fucosyl GM1 and GD1a) containing N-acetylneuraminic acid and N-glycolylneuraminic acid were obtained from plasma.

Caracterizaçäo imunológica do fator agregador das plaquetas (PAF) no plasma circulante do boi / Immunological characterization of platelet aggregation factor (PAF) in bovine circulating plasma

A metodologia utilizada em experiências anteriores para a purificaçäo e caracterizaçäo do PAF bovino foi também empregada para o estudo da molécula do PAF no plasma circular do boi. Ao contário do que se esperava, a imunoeletroforese cruzada do plasma de boi em gel de agarose a 2% näo forneceu os resultados esperados. A utilizaçäo, poré, de gel de agarose a 1% e a 0,8% permitiu o paparecimento de vários picos de imunoprecipitado com identidade total, tendo o gel a 0,8% fornecido uma resoluçäo maior. A vaiaçäo da distância dos orifícios à linha demarcadora entre o gel superior e o gel inferior foi também estudada. Os melhores resultados foram obtidos quando os orifícios se situavam próximos da linha de separaçäo. Esses achados confirmam os resultados de experiências anteriores e sugerem que o PAF circula no plasma de boi como uma série de agregados de altos pesos moleculares