TRANSFUSÃO DE PLASMA CONVALESCENTE EM COVID19: ASSOCIAÇÃO ENTRE ANTICORPOS NEUTRALIZANTES E REDUÇÃO DE CARGA VIRAL

Introdução

A transfusão de plasma convalescente tem sido utilizada como terapêutica alternativa no tratamento de COVID19 nos últimos meses. Avaliamos o impacto dos anticorpos neutralizantes produzidos pelos pacientes e dos anticorpos presentes nas unidades transfundidas na redução da carga  viral em pacientes em tratamento hospitalar de COVID19.

Materiais e métodos

Foram avaliados consecutivamente 29 pacientes admitidos para tratamento hospitalar de COVID19 em um único centro. Doses de 300 a 600 ml de plasma convalescente foram administradas ao longo de 2 dias. Foram coletados swabs nasais a cada 48 h a partir do D0 (dia de transfusão de plasma convalescente) até a alta hospitalar, a fim de determinar a carga viral por digital droplet PCR (ddPCR) dos alvos N1 e N2 do gene N (nucleocapsídeo) para análise de redução de carga viral, sendo considerado o número de cópias virais por 1000 células presente na amostra. Mensuramos os títulos de anticorpos neutralizantes (cytopathic effect-based virus neutralization test  -SARS-CoV-2 GenBank MT126808.1) dos pacientes (NAbsP) antes da transfusão (D0)  e títulos de anticorpos neutralizantes das unidades de plasma transfundidas (NAbsT). Para análise de associação entre NAbsP e redução de carga viral, os pacientes foram divididos em dois grupos de acordo com o status de NAbsP no D0: título de NabsP inferior a 80 e título de NabsP igual ou superior a 80. Para esta análise, foi utilizado o teste de Mann-Whitney . Para verificar a associação entre NAbsT e redução de carga viral, os pacientes foram divididos em três grupos: aqueles que receberam transfusão de plasma convalescente com título de NAbsT até 160, título de NAbsT entre 160-640 e NAbsT superior a 640. Para esta análise, foi utilizado o  teste de Kruskall-Wallis.

Resultados

Pacientes com baixos títulos de neutralizantes à admissão (NAbsP inferior a 80) apresentaram redução de carga viral significativamente maior (p=0,009) que pacientes com NAbsP igual ou superior a 80. Com relação ao impacto da transfusão de plasma, observou-se que quanto maior o título de anticorpos neutralizantes transfundidos maior foi a redução da carga viral; porém, tal achado não apresentou significância estatística (p = 0,528).

Discussão

O combate e eliminação da viremia através dos anticorpos neutralizantes presentes no plasma convalescente compreende uma das justificativas da sua aplicação como terapia alternativa para COVID19. Contudo, estudos prévios demonstraram resultados contraditórios em relação ao seu impacto no clearance viral. Na presente casuística, pacientes com baixos títulos de anticorpos neutralizantes apresentaram maior redução de carga viral após a transfusão de plasma convalescente do que pacientes com altos títulos. Pacientes que já apresentavam títulos elevados de neutralizantes parecem não se beneficiar da transfusão de plasma no que se refere à redução de carga viral. A estratificação dos pacientes de acordo com os níveis basais de anticorpos neutralizantes parece ser um ponto importante a ser discutido no tratamento de COVID19 com plasma convalescente e fornece uma explicação plausível para os resultados controversos previamente observados.

Prolonged fasting followed by refeeding modifies proteome profile and parvalbumin expression in the fast-twitch muscle of pacu (Piaractus mesopotamicus)

Here, we analyzed the fast-twitch muscle of juvenile Piaractus mesopotamicus (pacu) submitted to prolonged fasting (30d) and refeeding (6h, 24h, 48h and 30d). We measured the relative rate of weight and length increase (RRI_length and RRI_weight), performed shotgun proteomic analysis and did Western blotting for PVALB after 30d of fasting and 30d of refeeding. We assessed the gene expression of igf-1, mafbx and pvalb after 30d of fasting and after 6h, 24h, 48h and 30d of refeeding. We performed a bioinformatic analysis to predict miRNAs that possibly control parvalbumin expression. After fasting, RRI_length, RRI_weight and igf-1 expression decreased, while the mafbx expression increased, which suggest that prolonged fasting caused muscle atrophy. After 6h and 24h of refeeding, mafbx was not changed and igf-1 was downregulated, while after 48h of refeeding mafbx was downregulated and igf-1 was not changed. After 30d of refeeding, RRI_length and RRI_weight were increased and igf-1 and mafbx expression were not changed. Proteomic analysis identified 99 proteins after 30d of fasting and 71 proteins after 30d of refeeding, of which 23 and 17, respectively, were differentially expressed. Most of these differentially expressed proteins were related to cytoskeleton, muscle contraction, and metabolism. Among these, parvalbumin (PVALB) was selected for further validation. The analysis showed that pvalb mRNA was downregulated after 6h and 24h of refeeding, but was not changed after 30d of fasting or 48h and 30d of refeeding. The Western blotting confirmed that PVALB protein was downregulated after 30d of fasting and 30d of refeeding. The downregulation of the protein and the unchanged expression of the mRNA after 30d of fasting and 30d of refeeding suggest a post-transcriptional regulation of PVALB. Our miRNA analysis predicted 444 unique miRNAs that may target pvalb. In conclusion, muscle atrophy and partial compensatory growth caused by prolonged fasting followed by refeeding affected the muscle proteome and PVALB expression.

Changes in amounts of total salivary gland proteins of Lutzomyia longipallpis (Diptera: Psychodidae) according to age and diet

Saliva plays important roles in facilitation of a bloodmeal, lubrication of mouthparts, and parasite transmission for some vector insects. Salivary composition changes during the lifetime of an insect, and differences in the salivary profile may influence its functions. In this report, the amount and profile of salivary gland protein of the American visceral leishmaniasis vector Lutzomyia longipalpis (Lutz & Neiva, 1912) were analyzed at different times of insect development and diet. Protein content from unfed female sand flies increased significantly with age, and a significant difference was observed in sugar-fed females during the first 10 d of adult life. Salivary protein content sharply decreased 1 d after blood feeding, with gradual increase in concentration the following days. SDS-polyacrylamide gel electrophoresis analysis revealed that most polypeptides present in the saliva of sugar-fed also were present in the saliva of blood-fed females. Understanding changes in sand fly's saliva contents at distinct days after emergence and the influence of a bloodmeal in this aspect may reveal the role played by saliva during leishmaniasis transmission.

Case report: plexiform schwannoma of the vulva

We describe a case of plexiform schwannoma, a benign tumour of the peripheral nerve sheath, arising in the labia of a 5-year-old girl who presented with a mass in the vulva. Light and electron microscopy, special stains and immunohistochemistry studies were done on the excised specimen. A Medline search revealed a single case of vulvar plexiform schwannoma which was reported in 1983.

Cystadenoma of the seminal vesicle: report of a case with ultrastructural findings

Cystadenomas of the seminal vesicles are extremely rare benign tumours. We have not been able to find more than 10 cases in the literature. A benign cystadenoma of the seminal vesicle is described in a 49-year-old man. The clinical presentation, gross appearance, microscopic characteristics, immunohistochemical and ultrastructural findings of this uncommon tumour are discussed. The purpose of this paper is to report an unusual case of cystadenoma of the seminal vesicle and review the 10 previously reported cases in the English literature.

[Carotid body tumors: review of 8 cases and surgical approach]

Carotid body tumors are rather uncommon. Even though there is a great amount of literature on the subject, the controversy regarding its biological behavior and therapeutics and mainly, the surgical management still remains. We present eight patients with carotid body tumors (total of 9 tumors, one bilateral) surgically treated at the Neurosurgery Department of Santa Casa in Belo Horizonte, from 1989 to 1999. The age ranged from 11 to 66-years-old (35,6+/-17.7). Four patients were women and four were men. We had satisfactory postoperative results with low morbidity and no deaths. Based on our experience and on the review of the literature, some aspects of this disease are discussed. We conclude that carotid body tumors are uncommon and should be treat with carefully surgery techniques to obtain low morbi-mortality rates.

Placental site nodules and plaques: a clinicopathological and immunohistochemical study of 25 cases with ultrastructural findings

Placental site nodules or plaques (PSN-Ps) are nodular benign lesions of the intermediate trophoblast (IT) cells in the endometrium, endocervix, superficial myometrium or fallopian tube, occurring after a remote intrauterine pregnancy. We present a study of 25 cases of PSN-Ps These lesions occurred in patients aged 18 to 44 years. Most were discovered incidentally in endometrial curettage specimens. The specimens were received as part of clinical investigations for menorrhagia, per vaginal bleeding or pelvic pain. None of the PSN-Ps was visible grossly. Microscopically, they were mostly multiple, well-circumscribed, oval or plaque-like cellular nodules. The IT cells typically had abundant vacuolated or eosinophilic cytoplasm. The nuclei were irregular, large, hyperchromatic, often degenerate-looking and either mononucleated, multinucleated or multiclefted. Hyalinization surrounding individual or groups of IT cells, or located in the centre of the nodules, was a constant feature in all cases. The lesional cells were strongly immunoreactive to CAM 5.2, 34 beta E12, AE1/AE3, EMA and vimentin. Some cases showed focal positivity to HCG and HPL. PLAP staining was consistently negative. Ultrastructurally, the IT cells showed prominent nuclear variation in size and shape. The abundant, vacuolated cytoplasm contained some rough endoplasmic reticulum and loosely arranged filaments. This study describes the clinicopathological and immunophenotypic features of 25 cases of PSN-Ps including the ultrastructural findings of one case.

Chromoblastomycosis: a retrospective study of six cases at the Royal Darwin Hospital from 1989 to 1994

Chromoblastomycosis, a localized chronic cutaneous and subcutaneous infection of the skin caused by pigmented fungi, is most common in the world's tropical and subtropical zones. The condition rarely occurs in Australia. We present 6 cases of chromoblastomycosis seen at the Royal Darwin Hospital, Northern Territory, from 1989 to 1994 and affecting predominantly male Caucasians ranging from 38 to 71 yrs of age. Clinically the lesions were verrucous or nodular. They mimicked basal or squamous cell carcinoma, nevi or solar keratoses. Histopathologic findings were nonspecific. The only pathognomonic finding was the presence of brown spores or sclerotic bodies within granulomata or within microabscesses in the skin.

Coronary artery thromboembolism and unexpected death in childhood and adolescence

Two cases of unexpected death in childhood and adolescence associated with coronary artery thromboembolism are reported involving a 6-year-old girl with acute rheumatic fever and left ventricular vegetations, and an 18-year-old adolescent with Down syndrome and congenital heart disease. Although coronary artery thromboembolism is rarely reported in childhood or adolescence, these cases demonstrate that careful examination of the coronary arteries during pediatric autopsy may be helpful in determining factors contributing to death, even at quite young ages. This is particularly so in the presence of predisposing cardiac pathology.

Cementifying fibroma of the maxillary antrum

A 26 yr old Caucasian, previously healthy, noticed a painless swelling of the left palate of 2 mths duration. On examination, a left maxillary swelling was noted with extension into the cheek. The mass was compressible. The CT scan revealed a large expansive tumor. Histological diagnosis of the enucleated lesion was cementifying fibroma. We describe a case of cementifying fibroma of the maxilla, an unusual location for this tumor.