Ainda não está clara a eficácia dos parâmetros hematológicos no fechamento da persistência do canal arterial (PCA). O objetivo principal do nosso estudo é investigar o efeito da proporção (HRR) de largura de distribuição de hemoglobina (HB) para glóbulos vermelhos (RDW) no fechamento do PCA. Bebês prematuros com muito baixo peso ao nascer (MBPN: <1.500 g) e <32 semanas gestacionais foram incluídos no estudo, e todos os dados foram registrados retrospectivamente. Características demográficas, resultados clínicos, parâmetros de hemácias e HRR e suas proporções foram comparados entre grupos de PCA hemodinamicamente significativa (hsPDA) e não-hsPDA. Todos os resultados foram analisados estatisticamente, e p<0,05 foi considerado estatisticamente significativo. Um total de 677 bebês prematuros, 269 no grupo hsPDA e 408 no grupo não-hsPDA, foram incluídos no estudo. Hemoglobina (HB), hematócrito (HCT), volume celular médio (VCM), glóbulos vermelhos (RBC), largura de distribuição dos glóbulos vermelhos (RDW), volume plaquetário médio (VPM), relação VCM/RBC, relação HB/RBC, RDW A razão /RBC e a razão RDW/VPM foram semelhantes entre os grupos hsPDA e não hsPDA, . HRR foi significativamente menor no grupo hsPDA  em comparação com não-hsPDA  . A AUC para o valor diagnóstico de HRR em hsPDA foi de 0,816 e o valor de corte foi ≤0,98 . O valor de HRR foi considerado um parâmetro eficaz e poderoso no diagnóstico de hsPDA. A persistência do canal arterial (PCA) é a doença cardíaca mais comum em prematuros. Há uma taxa crescente de morbidade e mortalidade relacionada à PCA em prematuros. O shunt da esquerda para a direita devido à PCA causa diminuição do fluxo sanguíneo sistêmico e aumento do fluxo sanguíneo pulmonar. Como resultado, há um risco aumentado de morbidades graves, como edema pulmonar e sangramento, aumento da necessidade de suporte respiratório, hemorragia intraventricular (HIV), leucomalácia periventricular, enterocolite necrosante (ECN), retinopatia da prematuridade (ROP), displasia broncopulmonar (DBP) e resultados de neurodesenvolvimento ruins.A falha no fechamento do canal arterial (CA) dentro de 72 horas é definida como PCA. A frequência de PCA é inversamente proporcional à semana gestacional (SG) e ao peso ao nascer (PN). A incidência de PCA é de 60-70% em prematuros com menos de 28 SG e 20% em prematuros <32 semanas de gestação. A PCA é observada em uma taxa de 40-55% em bebês com peso corporal <1.000 g e 30% em bebês com peso corporal <1.500 g.O fechamento funcional do DA ocorre logo após o nascimento devido ao aumento da saturação de oxigênio e diminuição dos níveis de prostaglandina. Dano endotelial, ruptura subintimal, interação plaqueta-endotelial, proliferação neointimal e formação de estrutura fibrosa vascular são eficazes no fechamento anatômico. Embora os efeitos de SG, PN e os mecanismos acima no fechamentoductal sejam conhecidos, outros mecanismos que afetam o fechamento ductal não são totalmente compreendidos. Além disso, os parâmetros hematológicos também podem afetar o fechamento ductal. Muitos estudos avaliam a relação entre contagem de plaquetas, índices e funções e PCA. No entanto, existem poucos estudos sobre o efeito dos eritrócitos e parâmetros relacionados no fechamento ductal. Atualmente, o efeito dos parâmetros hematológicos no PCA não foi totalmente elucidado. Um pequeno número de estudos em adultos concluiu que a proporção (HRR) da largura de distribuição (RDW) da hemoglobina (HB) para os glóbulos vermelhos pode ser um marcador prognóstico em alguns tipos de câncer. Estudos recentes determinaram que o baixo valor de HRR em adultos com insuficiência cardíaca e doença cardíaca coronária é um fator de risco independente para mortalidade e resultados clínicos adversos. No entanto, não foi avaliado se a HRR pode ser um parâmetro preditor na PCA, que é o problema cardiovascular mais comum em recém-nascidos.Alguns marcadores e parâmetros bioquímicos podem afetar o fechamento ductal.O significado clínico de HRR na PCA não foi previamente avaliado. De acordo com a hipótese de nosso estudo, a HRR derivada de parâmetros hematológicos que podem afetar o fechamento ductal pode ser um novo parâmetro promissor. O objetivo principal deste estudo é avaliar a relação entre HRR e PCA. O objetivo secundário do nosso estudo é avaliar a relação entre PCA e outros parâmetros de hemácias no hemograma completo.Bebês prematuros com PN <1.500 g e SG <32 semanas foram elegíveis para o estudo. O estudo foi retrospectivo e os dados foram obtidos dos prontuários do hospital entre setembro de 2020 e novembro de 2021. Pacientes com grandes anomalias congênitas, cardiopatia congênita, asfixia perinatal, peso ao nascer ≥1.500 g e pacientes que morreram nos primeiros três dias após nascimento foram excluídos do estudo. As características demográficas e clínicas dos pacientes e os parâmetros dos glóbulos vermelhos no hemograma completo foram registrados. Os pacientes foram divididos em PCA hemodinamicamente significativa (hsPDA) e não hsPDA. A aprovação ética foi obtida do comitê de ética do hospital local antes de iniciar o estudo.Semana gestacional, PN, sexo, administração pré-natal de esteroides, escores de Apgar (aos 1 e 5 minutos), pequeno para a idade gestacional (PIG), síndrome do desconforto respiratório (SDR), HIV (grau ≥3), ECN (grau >2), DBP moderada/grave, ROP (requer terapia), sepse neonatal precoce (SNNP), sepse neonatal tardia (SNNT), ventilação mecânica (VM), ventilação não invasiva (VNI) e duração do oxigênio, alcançando o tempo total de alimentação enteral (dia), a duração da internação na unidade de terapia intensiva neonatal (UTIN) e as taxas de mortalidade foram registradas para todos os bebês. O diagnóstico de HIV grave (grau ≥3) foi demonstrado por ultrassonografia craniana. A classificação ECN (grau ≥2) foi feita com base em achados clínicos e laboratoriais. A DBP foi definida como pacientes com necessidade de oxigênio <30% (moderada) ou uso de oxigênio ≥30% ou pressão positiva (grave) na 36ª semana de idade pós-menstrual. Foram registradas as pacientes diagnosticadas com ROP de acordo com exame de retina realizado por um oftalmologista e posteriormente tratadas. Bebês com peso ao nascer abaixo do percentil 10 para SG foram definidos como PIG. Sepse pós-natal foi definida como SNNP se fosse ≤72 horas e SNNT se fosse >72 horas.Os pacientes que necessitam de tratamento com surfactante foram definidos como SDR. Se o diâmetro interno da PCA fosse <1,5 mm e/ou a relação átrio esquerdo/raiz da aorta fosse <1,5 por ECO, ou se a PCA não fosse detectada e se clinicamente e ecocardiograficamente fosse diferentes do hsPDA, esses pacientes foram incluídos no grupo não-hsPDA. Os pacientes do grupo hsPDA receberam terapia medicamentosa (anti-inflamatório não esteroide) pelo menos uma vez. Aqueles que não responderam a dois cursos de tratamento médico foram tratados cirurgicamente. A ingestão de líquidos foi iniciada em 70-80 mL/kg por dia em todos os lactentes e aumentada até um máximo de 150-160 mL/kg por dia em incrementos de 10-20 mL/kg por dia para todos os pacientes elegíveis.Seguindo o protocolo de nossa unidade, todos os pacientes do estudo recebem ecocardiografia Doppler (ECO) a cada 2 dias durante a primeira semana, a partir das primeiras 72 horas. Os pacientes foram diagnosticados com hsPDA de acordo com os critérios clínicos e ECO naDe acordo com o protocolo da unidade, amostras de sangue da veia umbilical foram coletadas em tubos de ácido etilenodiamino tetra-acético (EDTA) logo após o parto para um hemograma completo. Os valores de HB (g/dl), hematócrito , volume celular médio , glóbulos vermelhos , RDW (%) e volume plaquetário médio (VPM) foram analisados com hemocitômetro automático Cell-Dyn 3700 . O valor da HRR foi obtido dividindo HB por RDW. O valor da relação VCM/RBC foi obtido dividindo o VCM por RBC. A relação HB/RBC foi obtida dividindo HB por RBC. A razão RDW/RBC foi obtida dividindo RDW por RBC. A relação RDW/VPM foi obtida dividindo RDW por VPM.2 bilateral corrigido para continuidade em um nível de significância de 0,05.Após a transferência dos dados do paciente para o ambiente computacional, a análise estatística foi realizada com o programa Statistical Package for the Social Sciences (SPSS), versão 20.0 . Métodos visuais (gráficos de probabilidade e histograma) e analíticos (Teste de Kolmogorov-Smirnov) foram usados para avaliar as variáveis quanto à sua conformidade com a distribuição normal. O teste exato de Fisher ou o teste qui-quadrado de Pearson foi usado para avaliar as variáveis categóricas. Um teste t de Student não pareado ou teste U de Mann-Whitney foi aplicado para variáveis contínuas. As variáveis contínuas com distribuição normal foram apresentadas como média ± desvio padrão (DP), as variáveis com distribuição não normal foram apresentadas como mediana (Quartil 1 (Q1) - Quartil 3 (Q3)) (Q1 - Q3) e as variáveis categóricas foram apresentadas como frequência. A análise das curvas ROC (Receiver Operating Characteristics) foi realizada. Após a análise ROC, a área sob a curva (AUC) e o intervalo de confiança (IC) de 95% da AUC foram calculados. O limite do valor de HRR para fechamento ductal foi definido. A sensibilidade e a especificidade foram determinadas para o limiar do valor de HRR. Se o valor de p obtido fosse inferior a 0,05, era considerado estatisticamente significativo. O tamanho da amostra foi introduzido para o desfecho primário como fechamento ductal; 124 pacientes em cada grupo teriam 80% de poder para detectar uma diferença de 25% entre os grupos (de 60 a 85%) na porcentagem de fechamentos permanentes, usando um teste χUm total de 677 bebês MBPN que preencheram os critérios de inclusão foram alocados para o grupo de estudo. 269 pacientes foram incluídos no grupo hsPDA e 408 no grupo não hsPDA. No grupo hsPDA, o suporte respiratório , a obtenção de um dia completo de alimentação enteral e a permanência na UTIN foram mais longos. SDR, DBP, ROP, HIV e frequência de mortalidade foram significativamente maiores . Não houve diferença entre os dois grupos em relação à administração de esteroides pré-natal . Outras características demográficas e clínicas foram semelhantes entre os grupos  . DentreO objetivo principal do nosso estudo foi avaliar a relação da HRR com hsPDA. Este estudo descobriu que o valor de HRR no hemograma completo foi o parâmetro mais valioso para determinar hsPDA, com alta AUC, especificidade e sensibilidade entre os parâmetros de hemácias. Se o valor de HRR for ≤9,8, foi considerado altamente significativo para o risco de hsPDA. No entanto, nenhuma relação foi encontrada entre hsPDA e outros parâmetros de hemácias, que era nosso objetivo secundário. Além disso, a duração do suporte respiratório, o dia completo de alimentação enteral e a permanência na UTI foram maiores em lactentes com hsPDA. Os fatores de risco mais importantes para morbidade e mortalidade prematura foram SG e PN, pois SG e PN foram semelhantes em ambos os grupos. O aumento da taxa de morbidade prematura  e mortalidade no grupo hsPDA parecia ser devido ao efeito do hsPDA. Portanto, nossos resultados apoiaram o conhecimento de que hsPDA pode aumentar a morbidade e mortalidade prematura em bebês prematuros. Joye et al., relataram um aumento na frequência de hsPDA na presença de anemia grave que requer transfusão pós-parto. No mesmo estudo, interpretou-se que um nível de HB mais alto e estável nos primeiros dez dias de vida pode afetar positivamente o fechamento esperado do CA. Além disso, no estudo mencionado, o nível de HB foi >13,5 g/dL no grupo não hsPDA. Portanto, os autores sugeriram que o fechamento do CA pode ser sustentado por um maior nível de HB ou manutenção de um determinado nível de HB durante o período de transição. Nosso estudo não encontrou relação entre os valores de HB e HCT e hsPDA.Se os valores de HB e HCT diminuírem, a hipóxia tecidual aumenta. Sugere-se que o fechamento ductal diminuirá com o aprofundamento da hipóxia. No entanto, o efeito dos valores de HB e HCT no hsPDA não é totalmente conhecido. descobriram que a contagem absoluta de hemácias nucleadas era significativamente maior no grupo hsPDA do que no grupo não hsPDA. Especula-se que esse resultado se deva ao alto número absoluto de hemácias nucleadas e permeabilidade ductal após o parto devido à exposição à hipóxia fetal. Outro parâmetro dos glóbulos vermelhos, RDW, reflete a heterogeneidade no volume dos eritrócitos. Em seu estudo envolvendo 41 bebês prematuros, Garofoli et al., relataram que pacientes com hsPDA tinham um valor de RDW mais alto, e houve uma relação inversa entre os valores de RDW e SG. O aumento de RDW em pacientes com hsPDA pode ser decorrente da maior frequência de SNNT no grupo com hsPDA. Acredita-se que o aumento do RDW ocorra devido a citocinas inflamatórias que inibem a maturação eritrocitária e aceleram a transição de reticulócitos mais jovens e maiores para a circulação periférica. Estudos anteriores, incluindo maior número de pacientes, declararam não haver relação entre RDW e hsPDA. Nesses estudos, foi declarado que a frequência de sepse foi semelhante entre os grupos em paralelo aos nossos resultados. Portanto, RDW parece ser afetada principalmente pela inflamação relacionada à sepse em vez de hsPDA. Acredita-se que o aumento da RDW ocorra devido a citocinas inflamatórias que inibem a maturação eritrocitária e aceleram a transição de reticulócitos mais jovens e maiores para a circulação periférica. Estudos anteriores, incluindo maior número de pacientes, declararam não haver relação entre RDW e hsPDA.O efeito do VCM no fechamento ductal é desconhecido. Determinamos que o VCM não estava associado ao hsPDA. Assim, concluiu-se que o volume eritrocitário não afetou o fechamento ductal. Além disso, não encontramos nenhuma correlação entre o valor de RBC e hsPDA. A relação entre RBC e PCA não foi avaliada antes. No entanto, Bin-Nun et al., Também foi demonstrado que a relação RDW/RBC pode ser usada como um parâmetro eficaz para diferenciar beta-talassemia e deficiência de ferro. A relação RDW/RBC também foi relatada como um teste de triagem de α-talassemia. Além disso, foi declarado que tanto a relação RDW/RBC quanto RDW/VPM podem ser usadas como indicadores importantes no diagnóstico de apendicite aguda complicada em infância. A relação HB/RBC só foi estudada na toxicidade hepática. Foi demonstrado que a gravidade da toxicidade hepática e o valor da razão HB/RBC são diretamente proporcionais, sendo um parâmetro eficaz na demonstração do processo hemostático.A possível relação entre a relação VCM/RBC, HB/RBC, RDW/RBC e RDW/VPM com qualquer doença do recém-nascido não foi investigada. Verificou-se que VCM/RBC pode ser usada efetivamente para diferenciar anemia por deficiência de ferro e talassemia na infância. Portanto, as pesquisas continuam para outro parâmetro hematológico relacionado e preditivo que não é afetado pela inflamação para PCA, que é afetado principalmente por SG e PN e tem uma fisiopatologia mista. O fato de o parâmetro requerido estar associado à oxigenação tecidual, que tem efeito significativo no fechamento do CA, pode aumentar o valor de uso deste parâmetro. Portanto, o valor de HB tem uma relação paralela com a oxigenação tecidual; pode ser um parâmetro seguro na avaliação da relação entre HB e CA. Como a relação entre HB e PCA não é conhecida exatamente, o efeito dos parâmetros, incluindo HB, no processo de fechamento do duto deve ser avaliado. Em adultos, o significado prognóstico da HRR em pacientes com câncer tem sido objeto de estudos limitados. Foi relatado que está associado a um mau prognóstico de câncer abaixo de certos valores limiares para certos tipos de câncer. Por exemplo, valores de HRR de <0,989 em câncer de células escamosas de esôfago, <1,037 em câncer de cabeça e pescoço, <0,94 em câncer de bexiga músculo-invasivo, <0,948 em câncer de pulmão de células não pequenas e <1,01 em adenocarcinoma de pulmão são indicadores independentes para fatores de mau prognóstico dos pacientes. No estudo de Rahamim et al., no qual 6.888 pacientes adultos com insuficiência cardíaca foram avaliados, foi relatado que a HRR foi um parâmetro mais forte na predição de mortalidade do que a HB ou apenas RDW. A baixa HRR pode ser um preditor independente e forte de mortalidade e resultados clínicos adversos na doença coronariana. Além disso, HRR <9,76 foi o valor limite para o estado de fragilidade em doenças coronarianas. De acordo com nossos resultados, o valor de HRR < 0,98 obtido do cordão umbilical foi o parâmetro mais significativo para predizer hsPDA. Por outro lado, embora HB ou RDW sozinhos não tenham sido significativos na predição de hsPDA, descobriu-se que o valor de HRR obtido da razão desses dois parâmetros pode ser o marcador derivado de eritrócitos mais significativo e mais forte.Em nosso estudo, a relação entre a relação VCM/RBC, HB/RBC, RDW/RBC e RDW/VPM com hsPDA não pôde ser demonstrada. Os parâmetros usados em todas essas proporções são calculados sobre o volume ou largura de distribuição do eritrócito. O volume ou largura de distribuição dos eritrócitos muda em doenças onde a inflamação está em primeiro plano, incluindo sepse. Portanto, essas proporções provavelmente são um indicador de inflamação. Em nossos resultados, a incidência de sepse foi semelhante nos grupos com e sem hsPDA. Esse resultado sugere que a frequência de inflamação foi semelhante entre os grupos. Nossos resultados apoiaram a informação de que a relação VCM/RBC, relação HB/RBC, relação RDW/RBC e relação RDW/VPM foram particularmente afetadas em doenças causadas por inflamação. Quando HB e RDW foram usados como fatores prognósticos em estudos sobre tipos de câncer, nenhuma diferença significativa foi encontrada na sobrevida global. Em vez de avaliar apenas HB e RDW, como em nossos resultados, seu valor clínico torna-se significativo quando usado como HRR, que é uma razão entre si. Resultados semelhantes foram obtidos em estudos avaliando a relação entre insuficiência cardíaca e doenças coronarianas e HRR.Em estudos anteriores em pacientes com câncer, foi relatado que a HRR é um indicador do estado imunológico, nutricional e inflamatório. Embora a condição inflamatória básica, como sepse, tenha sido semelhante entre os grupos em nossos resultados, a menor HRR no hsPDA pode ser devida ao efeito do PCA na circulação, e não na inflamação. Assim, a HRR pode ser usada como um importante fator prognóstico que não é afetado por outros fatores de risco, incluindo a inflamação. De acordo com nossos resultados, foi revelado que a HRR era um parâmetro que também poderia ser usado para predizer hsPDA. No entanto, pensamos que a confirmação desses novos resultados com futuros estudos prospectivos seria benéfica.Uma vez que o valor de HB é afetado por sangramento e nutrição, e o valor de RDW é afetado por inflamação e infecção, isso limita seu uso como fator prognóstico específico da doença sozinho. Portanto, estudos anteriores mostraram que o uso de HB e RDW juntos como HRR, em vez de usar qualquer um deles como fator prognóstico sozinho, aumenta a significância clínica.O presente estudo é o primeiro a demonstrar a importância diagnóstica da HRR em prematuros com hsPDA. No entanto, nosso estudo atual tem algumas limitações. Uma dessas limitações é que a HRR é atualmente inválida para todos os prematuros devido ao desenho de estudo retrospectivo e de centro único. A segunda limitação é a ausência de um grupo controle de bebês nascidos a termo saudáveis. Além disso, estudos de eletroforese de hemoglobina que podem afetar os parâmetros eritrocitários não puderam ser realizados. Não realizamos parâmetros gasométricos. Finalmente, apenas os resultados do HRR na primeira amostra de sangue da veia umbilical pós-natal foram interpretados. Outros resultados de HRR em acompanhamentos diários não puderam ser avaliados.HB e RDW sozinhos não foram associados com hsPDA. No entanto, mostramos uma relação entre o valor de HRR no sangue do cordão umbilical e hsPDA. Usar HRR em vez de HB e RDW sozinho pode fornecer ao clínico informações valiosas para hsPDA. Também podemos supor que pode ser útil calcular a HRR em amostras de sangue coletadas durante o acompanhamento. Mais estudos são necessários para apoiar esta hipótese. Patent ductus arteriosus (PDA) is premature infants’ most common cardiac disease. There is an increasing rate of morbidity and mortality related to PDA in premature infants. Left-to-right shunting due to PDA causes decreased systemic blood flow and increased pulmonary blood flow. As a result, there is an increased risk of serious morbidities such as pulmonary edema and bleeding, increased need for respiratory support, intraventricular hemorrhage (IVH), periventricular leukomalacia, necrotizing enterocolitis (NEC), retinopathy of prematurity (ROP), bronchopulmonary dysplasia (BPD), and poor neurodevelopmental outcomes.thGW and 20% in premature infants <32 weeks of gestation. PDA is seen at a rate of 40-55% in infants with a BW of <1000 g and 30% in babies with a BW of <1500 g.Failure of the closer of ductus arteriosus (DA) within 72 hours is defined as PDA. The frequency of PDA is inversely proportional to the gestational week (GW) and birth weight (BW). The incidence of PDA is 60-70% in premature infants under 28Functional closure of the DA occurs soon after birth due to increased oxygen saturation and decreased prostaglandin levels. Endothelial damage, subintimal disruption, platelet-endothelial interaction, neointimal proliferation, and vascular fibrous structure formation are effective in anatomical closure. Although the effects of GW, BW, and the above mechanisms on ductal closure are known, other mechanisms affecting ductal closure are not fully understood.Additionally, hematological parameters may affect ductal closure. Many studies evaluate the relationship between platelet count, indices and functions, and PDA.However, few studies exist on the effect of erythrocytes and related parameters on ductal closure.Currently, the effect of hematological parameters on PDA has not been fully elucidated. A small number of adult studies concluded that hemoglobin (HB)-to-red cell distribution width (RDW) ratio (HRR) might be a prognostic marker in some cancer types.Recent studies have determined that low HRR value in adults with heart failure and coronary heart disease is an independent risk factor for mortality and adverse clinical outcomes.However, whether HRR can be a predictor parameter in PDA has not been evaluated, which is the most common cardiovascular problem in newborns.Some markers and biochemical parameters may affect ductal closure.The clinical significance of HRR in PDA has not been previously evaluated. According to the hypothesis of our study, HRR derived from hematological parameters that can affect ductal closure may be a new promising parameter. The primary aim of this study is to evaluate the relationship between HRR and PDA. The secondary aim of our study is to evaluate the relationship between PDA and other red cell parameters in the complete blood count.Premature infants with a BW of <1500 g and a GW of <32 weeks were eligible for the study. The study was retrospective, and data were obtained from the hospital’s medical records between September 2020 and November 2021. Patients with major congenital anomalies, congenital heart disease, perinatal asphyxia, birth weight ≥1500 g, and patients who died within the first three days after birth were excluded from the study. Demographic and clinical characteristics of the patients and red cell parameters in complete blood count were recorded. The patients were divided into hemodynamically significant PDA (hsPDA) and non-hsPDA. Ethical approval was obtained from the local hospital ethics committee before starting the study.Gestational week, BW, gender, antenatal steroid administration, Apgar scores (at 1 and 5 minutes), small for gestational age (SGA), respiratory distress syndrome (RDS), IVH (≥3 grade), NEC (grade >2), moderate/severe BPD, ROP (requiring therapy), early-onset neonatal sepsis (EOS), late-onset neonatal sepsis (LOS), mechanical ventilation (MV), noninvasive ventilation (NIV) and oxygen duration, achieving full enteral feeding time (day), neonatal intensive care unit (NICU) stay duration, and mortality rates were recorded for all infants.The diagnosis of severe IVH (≥3 grade) was demonstrated by cranial ultrasonography.NEC classification (≥2 grade) was made based on clinical and laboratory findings.BPD was defined as patients with a need for oxygen <30% (moderate) or receiving ≥30% oxygen or positive pressure (severe) at the 36thweek of postmenstrual age.Patients diagnosed with ROP according to the retinal examination performed by an ophthalmologist and subsequently treated were recorded.Babies with a birth weight below the 10thpercentile for GW were defined as SGA.Postnatal sepsis was defined as EOS if it was ≤72 hours and LOS if it was >72 hours.Patients requiring surfactant treatment were defined as RDS.If the PDA internal diameter was <1.5 mm and/or the left atrium/aortic root ratio was <1.5 by ECHO, or if PDA was not detected, and if clinically and echocardiographically other than hsPDA, these patients were included in the non-hsPDA group. Patients in the hsPDA group have received medical therapy  at least once.Those who did not respond to 2 courses of medical treatment were treated surgically. Fluid intake was initiated at 70-80 mL/kg per day in all infants and increased to a maximum of 150-160 mL/kg per day in increments of 10-20 mL/kg per day for all eligible patients.Following our unit protocol, all study patients receive Doppler echocardiography (ECHO) every 2 days during the first week, starting from the first 72 hours. The patients were diagnosed with hsPDA according to the clinical and ECHO criteria in6/µL), RDW (%), and mean platelet volume (MPV) values were analyzed with Cell-Dyn 3700 automatic hemocytometer . The HRR value was obtained by dividing HB by RDW. The MCV/RBC ratio value was obtained by dividing MCV by RBC. The HB/RBC ratio was obtained by dividing HB by RBC. The RDW/RBC ratio was obtained by dividing RDW by RBC. The RDW/MPV ratio was obtained by dividing RDW by MPV.According to the unit protocol, blood samples from the umbilical vein were taken into ethylenediamine tetra-acetic acid (EDTA) tubes soon after delivery for a complete blood count. HB (g/dl), hematocrit , mean cell volume , red blood cell , version 20.0  program. Visual (probability plots and histogram) and analytical methods (Kolmogorov-Smirnov Test) were used to evaluate the variables in terms of their conformity to the normal distribution. Fisher’s Exact test or Pearson Chi-Square test was used to evaluate categorical variables. An unpaired Student’s t-test or Mann-Whitney U test was applied for continuous variables. Normally distributed continuous variables were presented as mean ± standard deviation (SD), non-normally distributed variables were presented as median (Quartile 1 (Q1) - Quartile 3 (Q3)) (Q1 - Q3), and categorical variables were presented as frequency. Receiver operating characteristics (ROC) curves analysis was performed. After ROC analysis, the area under the curve (AUC) and the AUC’s 95% confidence interval (CI) were calculated. The threshold of HRR value for ductal closure was defined. Sensitivity and specificity were determined for the threshold of HRR value. If the obtained P value was below 0.05, it was considered statistically significant. The size of the sample was introduced for the primary endpoint as ductal closure; 124 patients in each group would have 80% power for detecting a 25% between-group difference (from 60 to 85%) in the percentage of permanent closures, using a two-sided, continuity-corrected χA total of 677 VLBW infants who met the inclusion criteria were allocated to the study group. 269 patients were included in the hsPDA group and 408 in the non-hsPDA group. In the hsPDA group, respiratory support , achieving a full enteral feeding day, and NICU stay were longer. RDS, BPD, ROP, IVH, and mortality frequency were significantly higher (p<0.05). There was no difference between the two groups regarding antenatal steroid administration (p>0.05). Other demographic and clinical characteristics were similar between the groups (p>0.05) . Among The primary aim of our study was to evaluate the relationship of HRR with hsPDA. This study found that the HRR value in the complete blood count was the most valuable parameter for determining hsPDA, with a high AUC, specificity, and sensitivity among the red cell parameters. If the HRR value was ≤9.8, it was found to be highly significant for the risk of hsPDA. However, no relationship was found between hsPDA and other red cell parameters, which was our secondary goal. Additionally, the duration of respiratory support, full enteral feeding day, and ICU stay were longer in infants with hsPDA. The most important risk factors for premature morbidity and mortality were GW and BW, as GW and BW were found to be similar in both groups. The increased rate of premature morbidity  and mortality in the hsPDA group seemed to be due to the effect of hsPDA. Therefore, our results supported the knowledge that hsPDA could increase premature morbidity and mortality in premature babies.Joye et al.reported an increase in the frequency of hsPDA in the presence of severe anemia requiring postpartum transfusion. In the same study, it was interpreted that a higher and more stable HB level in the first ten days of life may positively affect the expected closure of the DA. In addition, in the mentioned study, HB level was found to be >13.5 g/dL in the non-hsPDA group. Therefore, the authors suggested that the closure of the DA may be supported by a higher HB level or maintenance of a certain HB level during the transition period. Our study found no relationship between HB and HCT values and hsPDA. This result can be explained according to Joye’s hypothesis, as the HB value was >13.5 g/dL in both groups of patients.According to these results, the increased need for transfusion in patients with severe anemia increases the frequency of hsPDA and may decrease the response of hsPDA to the treatment.If HB and HCT values decrease, tissue hypoxia increases. It is suggested that ductal closure will decrease with the deepening of hypoxia. However, the effect of HB and HCT values on hsPDA is not fully known.found the absolute nucleated RBC count to be significantly higher in the hsPDA group than in the non-hsPDA group. It has been speculated that this result is due to high absolute nucleated RBC and ductal patency after delivery due to exposure to fetal hypoxia.Another red cell parameter, RDW, reflects the heterogeneity in erythrocyte volume. In their study involving 41 premature babies, Garofoli et al.reported that patients with hsPDA had a higher RDW value, and there was an inverse relationship between RDW values and GW.The increased RDW in patients with hsPDA may be due to the higher frequency of LOS in the group with hsPDA. The increase in RDW is thought to occur due to inflammatory cytokines that inhibit erythrocyte maturation and accelerate the transition of younger and larger reticulocytes to peripheral circulation.Previous studies, including higher numbers of patients, declared no relationship between RDW and hsPDA. In these studies, it was declared that the frequency of sepsis was similar between the groups as parallel to our results.Therefore, RDW seems to be primarily affected by sepsis-related inflammation rather than hsPDA.The increase in RDW is believed to be due to inflammatory cytokines that inhibit erythrocyte maturation and accelerate the transition of younger and larger reticulocytes to the peripheral circulation.27 Previous studies, including a larger number of patients, declared that there was no relationship between RDW and hsPDA.The effect of MCV on ductal closure is unknown. We determined that MCV was not associated with hsPDA. Thus, it was concluded that erythrocyte volume did not affect ductal closure. In addition, we could not find any correlation between RBC value and hsPDA. The relationship between RBC and PDA has not been evaluated before. However, Bin-Nun et al.It has also been shown that RDW/RBC ratio can be used as an effective parameter for differentiating beta-thalassemia and iron deficiency.The RDW/RBC ratio has also been reported to be used as an α-thalassemia screening test.In addition, it has been stated that both RDW/RBC ratio and RDW/MPV can be used as important indicators in diagnosing complicated acute appendicitis in childhood.The HB/RBC ratio has only been studied in liver toxicity. It has been shown that the severity of liver toxicity and the HB/RBC ratio value is directly proportional, and it is an effective parameter in demonstrating the hemostatic process.The possible relationship between the MCV/RBC ratio, HB/RBC ratio, RDW/RBC ratio, and RDW/MPV ratio with any disease of the newborn has not been investigated. It has been found that MCV/RBC can be used effectively to differentiate iron deficiency anemia and thalassemia in childhood.Therefore, the researches continue for other related and predictive hematological parameter that is not affected by inflammation for PDA, which is primarily affected by GW and BW and has a mixed pathophysiology. The fact that the required parameter is associated with tissue oxygenation, which has a significant effect on the closure of the DA, may increase the use value of this parameter. Therefore, the HB value has a parallel relationship with tissue oxygenation; it can be a safe parameter in evaluating the relationship between HB and DA. As the relationship between HB and PDA is not known exactly, the effect of the parameters, including HB, on the closure process of the duct should be evaluated. In adults, the prognostic significance of HRR in cancer patients has been the subject of limited studies. It has been reported to be associated with a poor prognosis of cancer below certain threshold values for certain cancer types. For example, HRR values of <0.989 in esophageal squamous cell cancer, <1.037 in head–neck cancer, <0.94 in muscle-invasive bladder cancer, <0.948 in non-small cell lung cancer, and <1.01 in lung adenocarcinoma are independent indicators for poor prognostic factors of patients.In the study of Rahamim et al.,in which 6888 adult patients with heart failure were evaluated, it was reported that HRR was a stronger parameter in mortality predictivity than HB or RDW alone.Low HRR may be an independent and strong predictor of mortality and adverse clinical outcomes in coronary heart disease. In addition, HRR <9.76 was found to be the threshold value for the state of frailty in coronary heart diseases.According to our results, the HRR value of <0.98 obtained from the umbilical cord was the most significant parameter to predict hsPDA. On the other hand, while HB or RDW alone was not significant in predicting hsPDA, it was found that the HRR value obtained from the ratio of these two parameters could be the more significant and strongest erythrocyte-derived marker.In our study, the relationship between MCV/RBC ratio, HB/RBC ratio, RDW/RBC ratio, and RDW/MPV ratio with hsPDA could not be demonstrated. The parameters used in all these ratios are calculated over the volume or distribution width of the erythrocyte. The volume or distribution width of the erythrocyte changes in diseases where inflammation is at the forefront, including sepsis. Therefore, these ratios are likely to be an indicator of inflammation. In our results, the sepsis incidence was similar in groups with and without hsPDA. This result suggested that the frequency of inflammation was similar between the groups. Our results supported the information that MCV/RBC ratio, HB/RBC ratio, RDW/RBC ratio, and RDW/MPV ratio were particularly affected in diseases caused by inflammation.When HB and RDW were used as prognostic factors in studies on cancer types, no significant difference was found in overall survival. Instead of evaluating HB and RDW alone, as in our results, their clinical value becomes meaningful when it is used as HRR, which is a ratio to each other.Similar results were obtained in studies evaluating the relationship between heart failure and coronary heart diseases and HRR.In previous studies in cancer patients, it has been reported that HRR is an indicator of immune, nutritional and inflammatory status.While the basic inflammatory condition, such as sepsis, was similar between the groups in our results, the lower HRR in hsPDA may be due to the effect of PDA on circulation rather than inflammation. Thus, HRR can be used as an important prognostic factor that is not affected by other risk factors, including inflammation.According to our results, it was revealed that HRR was a parameter that could also be used to predict hsPDA. However, we thought confirming these new results with future prospective studies would be beneficial.Since the HB value is affected by bleeding and nutrition, and the RDW value is affected by inflammation and infection, it limits its use as a disease-specific prognostic factor alone. Therefore, previous studies have shown that using HB and RDW together as HRR rather than using either as a prognostic factor alone increases the clinical significance.The present study is the first to demonstrate the diagnostic importance of HRR in premature infants with hsPDA. However, our current study has some limitations. One of these limitations is that the HRR is currently invalid for all premature infants due to the single-center and retrospective study design. The second limitation is the absence of a healthy-term infant control group. In addition, hemoglobin electrophoresis studies that may affect erythrocyte parameters could not be performed. We did not perform blood gas parameters. Finally, only the results of the HRR in the first postnatal umbilical vein blood sample were interpreted. Other HRR results at daily follow-ups could not be evaluated.HB and RDW alone were not associated with hsPDA. However, we showed a relationship between the HRR value in cord blood and hsPDA. Using HRR instead of HB and RDW alone can provide the clinician with valuable information for hsPDA. We can also assume that it may be useful to calculate the HRR in blood samples taken during follow-up. Further studies are needed to support this hypothesis.


Background: Frequently used physical therapy (PT) equipment is notably difficult to disinfect due to equipment material and shape, however, the efficacy of standard disinfection of PT equipment is poorly understood. Methods: We completed a prospective observational microbiological analysis of fomites used in adult or pediatric PT at Duke University Health System, Durham, North Carolina, from September to December 2022. Predetermined study fomites were obtained after being used during a clinical shift and standard disinfection had been completed by clinical service staff. Fomites were split into 2 halves, left and right, for sampling. Samples were taken with premoistened cellulose sponges processed using the stomacher technique and were incubated on appropriate selective and general medias. We defined antimicrobial-resistant, clinically important pathogens (AMR-CIP) as MRSA, VRE, and MDR-gram-negative isolates, and non–AMR-CIP as MSSA, VSE, and gram-negative species. Study fomites were grouped as follows: (1) pediatric pig toy, (2) walking aids , (3) balls , and (4) other . Results: In total, 47 patients, 61 fomites, and 122 were analyzed. Of the study patients, 24 (51%) were female, 13 (27%) had active infections, and 15 (32%) were on contact precautions. Because fomites were split in half, patients in the left and right study arms were identical. Overall, the median total colony-forming-units (CFU) of study fomites was 1,348 : 468  for the left side study arm and 540  for the right study arm (P = .45). At the sample level, 52 (43%), 15 (12%), and 37 (30%) of 122 samples harbored any CIPs, AMR CIPs, or non-AMR CIPs, respectively. At the fomite level, 27 (44%), 5 (8%), 15(25%), and 7 (11%) of 61 fomites harbored any CIPs, only AMR-CIPs, only non-AMR CIPs, or both AMR and non-AMR CIPs, respectively. Generally, therapy balls were the most contaminated study fomites , and walking aids were most frequently contaminated with any CIPs , AMR CIPs , and non-AMR CIPs . Discussion: Following routine disinfection, frequently used PT equipment remained heavily contaminated and harbored AMR and non-AMR CIPs, supporting the notion that PT equipment is difficult to disinfect via standard disinfection. Additionally, left-, and right-side fomite divisions had similar pathogens, suggesting that this sampling model of intrapatient comparisons may be helpful for resolving case-mix issues in future studies. Future work should focus on PT-specific enhanced disinfection strategies to improve the disinfection of PT equipment.Financial support: This study was funded by PURioLABS.Disclosures: None


The emergence and spread of antimicrobial resistance (AMR) and resistant bacteria, are a global public health challenge. Through horizontal gene transfer, potential pathogens can acquire antimicrobial resistance genes (ARGs) that can subsequently be spread between human, animal, and environmental reservoirs. To understand the dissemination of ARGs and linked microbial taxa, it is necessary to map the resistome within different microbial reservoirs. By integrating knowledge on ARGs in the different reservoirs, the One Health approach is crucial to our understanding of the complex mechanisms and epidemiology of AMR. Here, we highlight the latest insights into the emergence and spread of AMR from the One Health perspective, providing a baseline of understanding for future scientific investigations into this constantly growing global health threat. •AMR is a leading and constantly growing threat to global health.•The human microbiome is an important AMR reservoir.•Human–animal–environment interactions favor AMR dissemination.•One Health is crucial for understanding AMR transmission and spread. Current Opinion in Microbiology 2023, 73:102291MicrobiotaThis review comes from a themed issue on Christopher Stewart and Maria Carmen ColladoEdited by Microbiota”For complete overview of the section, please refer to the article collection, “https://doi.org/10.1016/j.mib.2023.102291http://creativecommons.org/licenses/by/4.0/).1369–5274/© 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license . Throughout history, bacterial infections have been a major cause of human and animal diseases. The discovery and use of antibiotics enabled their effective management from a clinical point of view, but at the same time resulted in increased AMR. If no measures are undertaken to mitigate the current rates of emergence and spread of AMR, it is estimated that AMR will result in a financial burden of 100 trillion dollars at the global level and cause over 10 million deaths per year by 2050 Human health is tightly linked to the health of animals and the ecosystems they share, enabling resistant bacteria or antimicrobial resistance genes (ARGs) to spread between different human, animal, and environmental reservoirs. These phenomena have the potential to rapidly trigger a pandemic, whereby AMR is no longer constrained by either geographic or human–animal borders In this review, we highlight the latest insights into the emergence and spread of AMR from the One Health perspective, thereby providing a baseline reference of understanding for future scientific investigations into this leading and constantly growing global health threat.Klebsiella pneumoniaeStaphylococcus aureus (MRSA) can transfer MGEs, which are too large to be packed into phages, to methicillin-sensitive Staphylococcus aureus strains by natural transformation in biofilms Bacteria have evolved various counteractive mechanisms to confer resistance to antimicrobial agents and assure their survival in a competitive environment Resistant bacteria residing within human, animal, and environmental reservoirs may spread from one to another, at both local and global levels . The rolEnterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli pathogens that are highly resistant to last-resort drugs and extensively described in different microbial reservoirs Campylobacter jejuni for which infections have been reported in humans, animals, and the environment Salmonella has been identified in human Many studies have focused specifically on the In the context of One Health, natural microbial communities, or microbiomes, may also have an important role in the dissemination of AMR. The structure of human and animal microbiomes is shaped by several factors, including exposure to microorganisms through contacts with exogenous sources , specific host–microbe interactions, and the outcome of competitive, cooperative, and/or predatory (phage) interactions Klebsiella pneumoniae, ESBL-, AmpC-, and carbapenemase-producing Escherichia coli, carbapenem-resistant Acinetobacter baumannii and Pseudomonas aeruginosa, vancomycin-resistant Enterococcus faecium, MRSA, penicillin-resistant Streptococcus pneumoniae, as well as fluoroquinolone-resistant Salmonella and Shigella species. More recently, lesser-known human pathogens such as Corynebacterium diphtheriae isolates have been reported to carry penicillin, macrolide, and multidrug resistance et al. revealed a Pseudomonas aeruginosa-resistant lineage within the gut of a critically ill individual demonstrating local resistance adaptation due to the organ-specific selective pressure. Subsequently, the same strain was found in the lung suggesting within-host transmission as one of the AMR dissemination mechanisms The prevalence of AMR and the studies thereof have mostly been limited to clinically relevant pathogenic bacteria. These include but are not limited to extended-spectrum beta-lactamase (ESBL)-producing and carbapenem-resistant Escherichia coli and Streptococcus pneumoniae was decreased during 2020, likely due to the sanitary measures implemented to prevent the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, Acinetobacter spp. and Enterococcus faecium, resistant bacteria usually present in the hospital environments, were more frequently observed during the same period Transmission of AMR has been extensively discussed in the context of sanitary conditions, such as open defecation or access to clean water Enterococcus spp. Antibiotics are extensively used in livestock and poultry, especially in food production, leading to microbial community compositional shifts and potential increase in ARGs. Treatments using antibiotics in the animal industry also raise the risk of emergence of resistant bacteria due to longer-term selective pressures. In this context, an increased AMR abundance was detected in the gut of farm animals  compared with wild animals  Salmonella from poultry Escherichia coli from veal calves Escherichia coli from pigs Pseudomonas, Stenotrophomonas, and Myroides species, were identified in a variety of seafood products Though the emergence of resistant pathogens is a critical consideration, the spread of ARGs from animal to the human microbiome is of more immediate concern. Such spread can occur via multiple routes, including the direct transmission through food products. Multiple studies have reported food animals as a source of AMR, including multidrug-resistant Enterococcus spp., Salmonella spp., and Vibrio spp.) in migratory birds Escherichia coli in Bangladesh Extensively used concentrated animal feeding operations have also been recognized as AMR reservoirs and a source of resistant bacteria  contribute to the evolution and spread of AMR through coselection. Heavy metal contamination, for example, coelects antibiotic and metal resistance by cross-resistance, where single genetic mutation may mediate resistance to both metals and antibiotics, or co-resistance, where both metal- and antibiotic-resistance genes are localized on the same MGE Traditionally, culture-based methods are used in clinical settings to investigate AMR and resistant bacteria de novo assembly-based methods de novo reconstruction of genomic fragments. Though available studies report the cross-reservoir similarities and likely transmission of AMR in a One Health setting, there is a need for more in-depth characterization of AMR transmission mechanisms, including methods to determine and classify transmission.To investigate the presence of AMR and MGEs within metagenomes, different bioinformatic workflows, read-, and AMR is an ever-present concern, not necessarily due to the use of antibiotics alone, but also due to anthropogenic impact and rapid globalization. A major challenge still faced by most One Health studies is attributing the directionality of ARGs between the different metagenomes. To accurately reconstruct the patterns of transmission, especially the directionality of transmission, approaches combining (meta)genomic data analysis, including phylogenetic analysis, with epidemiological approaches and time series, are needed. Since it is evident that AMR reservoirs may affect each other and given the potential role of human and animal microbiomes in AMR, understanding the interactions/mechanisms and role of each component contributing to the spread of AMR is a critical step in monitoring and addressing this challenge for human health and well-being. Recognizing the microbial reservoirs of AMR is an important first step toward this goal. Furthermore, combined methods incorporating the identity of ARGs, modes of transmission, and integration into the individual reservoirs, alongside crossover mechanisms, may be needed for comprehensive characterization of AMR dissemination. Given the dynamic interactions between humans, animals, and the environment, information on directionality in the One Health context will propel better understanding and management of the different reservoirs, especially in terms of anthropogenic effects. This will allow better antibiotic stewardship contributing to effective treatments using existing antibiotics.Not applicable.10.13039/501100000781European Research Council [ERC-CoG 863664]. L.dN. and P.W. were supported by the Luxembourg National Research Fund (FNR) [PRIDE17/11823097]. S.B.B. was supported by the Synergia grant [CRSII5_180241] through the 10.13039/501100001711Swiss National Science Foundation. P.W. and M.D. are supported by the Luxembourg Government through the CoVaLux programme.P.W. acknowledges the Not applicable.The authors consent to publication.LdN designed and created the overview figure. MD, SBB, LdN, and PW conceptualized the review and contributed to the writing.The authors do not have any conflicts of interest relating to this work.


We linked the phylum Actinobacteria to soil-derived enediyne and cis-AT KSs while marine-derived KSs associated with enediyne and monomodular PKSs were linked to phyla from which the compounds produced by these biosynthetic enzymes have not been reported. These KSs were phylogenetically distinct from those associated with experimentally characterized PKSs suggesting they may be associated with novel structures or enzyme functions. Finally, we employed our metagenome-extracted KS domains to evaluate the PCR primers commonly used to amplify type I KSs and identified modifications that could increase the KS sequence diversity recovered from amplicon libraries.Microbial polyketide synthase (PKS) genes encode the biosynthesis of many biomedically or otherwise commercially important natural products. Despite extensive discovery efforts, metagenomic analyses suggest that only a small fraction of nature’s polyketide biosynthetic potential has been realized. Much of this potential originates from type I PKSs (T1PKSs), which can be further delineated based on their domain organization and the structural features of the compounds they encode. Notably, phylogenetic relationships among ketosynthase (KS) domains provide an effective method to classify the larger and more complex T1PKS genes in which they occur. Increased access to large metagenomic data sets from diverse habitats provides opportunities to assess T1PKS biosynthetic diversity and distributions through their smaller and more tractable KS domain sequences. Here, we used the web tool NaPDoS2 to detect and classify over 35,000 type I KS domains from 137 metagenomic data sets reported from eight diverse, globally distributed biomes. We found biome-specific separation with soils enriched in KSs from modular Polyketides are a crucial source of medicines, agrichemicals, and other commercial products. Advances in our understanding of polyketide biosynthesis, coupled with the increased availability of metagenomic sequence data, provide new opportunities to assess polyketide biosynthetic potential across biomes. Here, we used the web tool NaPDoS2 to assess type I polyketide synthase (PKS) diversity and distributions by detecting and classifying ketosynthase (KS) domains across 137 metagenomes. We show that biomes are differentially enriched in type I KS domains, providing a roadmap for future biodiscovery strategies. Furthermore, KS phylogenies reveal biome-specific clades that do not include biochemically characterized PKSs, highlighting the biosynthetic potential of poorly explored environments. The large metagenome-derived KS data set allowed us to identify regions of commonly used type I KS PCR primers that could be modified to capture a larger extent of environmental KS diversity. These results facilitate both the search for novel polyketides and our understanding of the biogeographical distribution of PKSs across Earth’s major biomes. Microorganisms are a valuable source of structurally diverse specialized metabolites, including many with clinically relevant biological activities , 2. Rececis-AT) where each KS domain catalyzes one round of chain elongation. Trans-AT PKS genes represent another version of these multimodular systems in which the AT domain occurs outside of the PKS gene  has identified previously unknown or poorly studied microbial taxa, including Acidobacteria and Candidatus Eremiobacteraeota from soils  and seawIn this study, we used NaPDoS2 to detect and classify type I KS domains from eight environmental biomes. Using KS phylogenies, we detected biome-specific clades that are distinct from those associated with experimentally characterized BGCs. Additionally, we show that less than 3% on average of the KS domains in each metagenome are associated with MAGs, supporting their value as a proxy to assess biosynthetic diversity. Finally, access to environmental KS sequences provided an opportunity to evaluate the effectiveness of a widely used type I KS primer set.cis-AT, trans-AT, and iterative cis-AT) and eight subgroups   . To valirans-AT) . In eachrans-AT) .cis-AT with no further subgroup designation. Following that, the iterative cis-AT PUFA (20.9%) and modular cis-AT hybrid (18.9%) designations were the next most abundant (The majority of metagenome-extracted type I KSs (37.5%) were classified by NaPDoS2 as abundant . We alsoabundant . This hiP < 0.001, R2 = 0.499] with PUFA, cis-AT, and hybrid cis-AT KS domains representing major drivers of biome separation between marine and non-marine samples (P < 0.01). Likewise, forest/agricultural soil and rhizosphere metagenomes encoded significantly more hybrid cis-AT KS domains per Gbp (P < 0.01), and forest/agricultural soil metagenomes encoded more cis-AT KS domains (P < 0.01) than non-soil biomes  based on a Bray–Curtis dissimilarity matrix showed a significant separation of biomes based on type I KS composition [permutational multivariate analysis of variance (ANOVA),  samples . To furt samples  than othl biomes .P < 0.01).To assess KS diversity across biomes, we focused on the 7,945 full-length KS domains that could be extracted across the metagenomes as they provide a standardized framework for comparison. To assess KS richness, we clustered these sequences into operational biosynthetic units (OBUs)  over a rWe next asked how the full-length KS sequences compared with those associated with experimentally characterized PKSs in the MIBiG 2.0 database. Regardless of biome, most sequences shared little similarity with the database, with only 1% overall sharing >90% amino acid sequence identity . The numWe next identified the number of KS domains in OBUs shared between biomes by rarefying each biome to 580 full-length KS sequences (the lowest number in any one biome), clustering the sequences into OBUs over a range of 70%–95% amino acid sequence identity, and performing pairwise comparisons . Overallcis-AT/iterative, 725 trans-AT, 126 hybrid cis-AT, 29 PUFA, and 11 enediyne KS domains). The hybrid cis-AT , trans-AT (n = 831), PUFA , and enediyne (n = 210) KS domains are clearly distinguished within the SSN. The cis-AT/iterative cluster  represents the fifth group and includes KSs classified by NaPDoS2 as modular (assembly line) cis-AT (including olefin synthase and loading module subgroups) and iteratively acting cis-AT (including iterative aromatic and iterative PTM subgroups). The three PUFA KS clusters correlate with the three KS domains that are usually found in PUFA PKSs (A sequence similarity network (SSN) was used to visualize relatedness among the 7,945 full-length metagenome-extracted KS domains in the context of their NaPDoS2 classification . AdditioUFA PKSs , 24. We cis-AT KS domains were a major driver of the separation among biomes  in which 98.0% of the sequences mapped to soil biomes  and non-soil (49.5%) biomes. Additionally, the phylogeny revealed a small clade of 89 sequences that originated from sponge metagenomes  that did not group with any MIBiG 2.0 sequences  and the NCBI RefSeq genome database (n = 271) after clustering into 70% OBUs. Enediynes represent a rare class of natural products that contain two acetylenic groups conjugated to a double bond within either a 9- or 10-membered ring. They are highly cytotoxic, have been developed into effective cancer drugs (n = 50) that co-localized with the genome-derived (NCBI RefSeq) sequences from Actinobacteria. This lineage encompassed all 11 MIBiG 2.0 enediyne KS domains (n = 31) observed in a large, sediment-specific clade. Sequences in this clade shared 85% or greater amino acid identity (NCBI BlastP) with a KS domain observed in the Deltaproteobacteria , trans-AT (n = 831), and PUFA KS domains  (cis-AT KS domains were most often assigned to Cyanobacteria (24.7%), the trans-AT KS domains to Gammaproteobacteria (27.0%) and Firmicutes (21.7%), and the PUFA KS domains to Deltaproteobacteria (27.7%). From the metagenome-extracted PUFA KS domains , over 92% fell outside of those associated with known products  . Based oproducts , suggestcis-AT, trans-AT, and hybrid cis-AT KSs across diverse bacterial phyla  and trans-AT (n = 831) KS domains, respectively, matched at the third-codon position (glutamine) from the 3′ end of the KS2F primer  targeted by the primer. If this 3′ position was modified to include isoleucine (I), the percentages for all KS sequence types would exceed 80%.The metagenome-extracted KS domains analyzed here are diverse in terms of their taxonomic affiliations and biome of origin. Importantly, they are not biased toward cultured strains. As such, we saw an opportunity to evaluate the commonly used type I KS primer set (KS2F/R), which has been shown to amplify al phyla -32. Whe primer . In contF primer . If thisn = 210) and PUFA  KSs matched the amino acids targeted by the second (arginine/serine) and fourth (glutamine) positions of the forward primer , hybrid cis-AT , and trans-AT (n = 831) KS domains after trimming them to an amplicon length typical of next-generation sequencing technologies (~138 amino acids). Overall, 94.6% of the shortened sequences yielded the same NaPDoS2 classification as their full-length counterparts . An SSN of the amplicon-length KS domains showed the same clustering pattern observed in the full-length KS domain SSN  metagenome-extracted main SSN , furthercis-AT modular and hybrid cis-AT KSs in soil biomes  and enediyne (28%) KS domains, whereas hybrid cis-AT, trans-AT, and PUFA domains mostly mapped to Cyanobacteria (24%), Gammaproteobacteria (28%), and Deltaproteobacteria (27%), respectively , resulting in a combined size of 240 Gbp. NaPDoS2  were selected from the JGI IMG database  and filt NaPDoS2  was useddatabase , and MAGdatabase .cis-AT, cis-loading module, olefin synthase, iterative aromatic, iterative PTM, trans-AT, hybrid trans-AT, hybrid cis-AT, PUFA, enediyne, and FAS. NaPDoS2 KS classifications were verified for a randomly selected subset of metagenomic sequences across the range of KS domain types by running the associated contigs through antiSMASH 6.0 .Full-length KS domains were filtered from the total type I metagenomic KS pool and the MIBiG 2.0 database . All typE-value edge calculation of 100 and visualized using Cytoscape , they were grouped by biome and clustered into 70% OBUs using UCLUST  were similarly clustered into 70% OBUs. Centroid representatives for each OBU were used to construct FastME trees using ngphylogeny.fr (n = 210) by extracting and clustering (70% OBUs) all enediyne KS domains from the RefSeq select genomes (n = 271) and MIBiG 2.0 (n = 11) databases. No clustering was needed prior to generating the trans-AT (n = 831), hybrid cis-AT , or PUFA  phylogenies.An SSN of all full-length sequences was constructed using EFI  with an ytoscape . Phyloge website  with def website . Due to g UCLUST . KS sequogeny.fr  under deogeny.fr . Similarcis-AT/iterative phylogeny, the relevant metagenomic contigs were analyzed using antiSMASH 5.0 (LIMV)) and the reverse primer 5′-GTNCNNGTNCCRTGNSCYTCNAC-3′ (translated to VE(AG)HGT(CWRSG)T). We aligned this primer set with the metagenome-extracted type I KS domains (amino acids), and the percent matching at each amino acid residue was calculated using Geneious ver. 2020.2 (The commonly used KS2F/KS2R -31 pri. 2020.2 . The PUF. 2020.2  was simi


Kaposi's sarcoma (KS) is a proliferative and multifocal disease with a double vascular and fibroblastic cell component, of mucocutaneous and visceral expression. It is a multifocal tumoral process, hyperplastic in nature without metastatic potential, induced by the human herpes virus 8 (HHV8). Paraneoplastic syndromes (PS) in KS are rare, with only a small number of cases reported and we have found no previous descriptions of a paraneoplastic scleroderma in KS in the literature. We report the cases of two patients with this atypical PS. Paraneoplastic syndromes (PS) in Kaposi Sarcoma are rare, with only a small number of cases reported and we have found no previous descriptions of a paraneoplastic scleroderma in KS in the literature. We report the cases of two patients with this atypical PS. It is a multifocal tumoral process, hyperplastic in nature without metastatic potential, induced by the human herpes virus 8 (HHV8).A paraneoplastic syndrome (PS) is a syndrome that is the consequence of neoplasia in the body, due to the production of chemical signalling molecules  by tumour cells or by an immune response against the tumour. Unlike a mass effect, it is not due to the local presence of cancer cells.PS in KS are rare, with only a small number of cases reported and we have found no previous descriptions of a paraneoplastic scleroderma in KS in the literature.We report the cases of two patients with this atypical PS.22.1An HIV‐negative 45‐year‐old Moroccan patient, with a history of pulmonary tuberculosis treated in 2020 presented with angiomatous nodules of the lower limbs with a scleroderma‐like condition that has been developing for 12 years. On clinical examination, we found ecchymotic purple nodules of hard consistency based on sclerotic plaques on the lower limbs, with sclerodactyly on the left side Figure . RaynaudThe clinical differential diagnosis of the sclerodactyly included systemic sclerosis, acrodermatitis chronica atrophicans, POEMS syndrome and a diabetic cheiroarthropathy.To rule out this diagnosis, a complete biologic work up was performed, including antinuclear antibodies (ANA) and borreliosis serology which were negative, and a protein electrophoresis which was normal. The electroneuromygram was normal.9/L . Immunoglobulin assay showed normal IgA 1.6 g/L , IgG 8.88 g/L , and IgM 0.8 g/L . The CD4 count was 503 cells/mm3 with a CD4/CD8 ratio of 1.2 and CD4% of 34.4%.Since the skin involvement was quite severe, extensive and disabling, the negativity of the HIV‐test was recontroled twice and also an immune workup was performed to look for an immune deficiency: Laboratory investigations on admission showed normal haemoglobin 13.3 g/dl , and white blood cell count 9.05 × 10Histological examination of the nodules showed spindle cells Figure  expressiThe extension assessment was carried out including a thoracic‐abdominal‐pelvic computed tomography scan and a fibrocolonoscopy which found no visceral involvement of KS nor systemic sclerosis.The patient was treated with ABV chemotherapy  due to extensive skin involvement. The evolution was marked by the worsening of the lesions motivating a therapeutic switch to paclitaxel and the patient died after three sessions of taxanes after a septic shock secondary to chemotherapy‐induced immune deficiency.2.2An HIV‐negative 50‐year‐old Moroccan patient previously healthy, presented with angiomatous nodular lesions localized on all four extremities, which had been developing for 2 years. Clinical examination also found lesions in favour of KS with a sclerodermiform appearance of the right hand characterized by irreducible flexion of the last three fingers Figure . In thisGiven the similar differential diagnosis as patient 1, the same biological and radiological assessment were performed eliminating the abovementioned diagnoses and no visceral involvement of KS or systemic sclerosis were found.A skin biopsy of the nodules confirmed KS Figure  and the Bleomycin‐based monochemotherapy was started for this patient, complicated by febrile pancytopenia, prompting the therapeutic switch to paclitaxel associated with growth factors.The evolution was marked by the improvement of KS lesions and incomplete regression of sclerodactyly.3KS is a multifocal disease. Its evolutionary spectrum ranges from an indolent locoregional form to a disseminated and fulminant form. PS in KS are rare, with only a small number of cases reported; autoimmune haemolytic anaemia is the most frequentDermatological paraneoplastic syndromes are a group of cutaneous or mucocutaneous syndromes characterized by their association with neoplasia and by a parallel evolution to the tumourThe elimination of other diagnoses that could induce a scleroderma‐like disorders helped us to retain the diagnosis of paraneoplastic scleroderma.Unfortunately in the first case, the patient died due to complications of chemotherapy, without having had time to see the evolution of the sclerotic lesions or the KS.For the second case, the evolution after treatment was marked by an incomplete resolution of the sclerodactyly. The improvement would be due to the treatment of the KS, which reinforces the theory of paraneoplastic scleroderma.The incomplete resolution of sclerodactyly is probably due to the importance of the fibrosis and its late stage.The association between KS and a scleroderma is unclear, we suggest that since in KS both fibroblasts and endothelial cells are infected by HHV8, inducing the production of pro‐angiogenic and inflammatory cytokines,Summing up, our case suggests the possibility of the development of scleroderma through paraneoplastic mechanisms in subjects affected with KS. Future studies to shed light on this theory are needed.The authors have no conflicts of interest to disclose.Sara Oulad Ali: Conceptualization ; Data curation ; Formal analysis ; Investigation ; Methodology ; Project administration ; Resources ; Software ; Supervision ; Validation ; Visualization ; Writing – original draft (Lead); Writing – review & editing (Lead). Belcadi Jihane: Conceptualization ; Data curation ; Formal analysis ; Investigation ; Methodology ; Project administration ; Resources ; Software ; Supervision ; Validation ; Visualization ; Writing – original draft (Supporting); Writing – review & editing (Supporting). Kawtar Znati: Conceptualization ; Data curation ; Formal analysis ; ; Investigation ; Methodology ; Project administration ; Resources ; Software ; Supervision ; Validation ; Visualization ; Writing – original draft (Supporting); Writing – review & editing (Supporting); Mariame Meziane: Conceptualization ; Data curation ; Formal analysis ; Investigation ; Methodology ; Project administration ; Resources ; Software ; Supervision ; Validation ; Visualization ; Writing – original draft (Supporting); Writing – review & editing (Supporting). Nadia Ismaili: Conceptualization ; Data curation ; Formal analysis ; Investigation ; Methodology ; Project administration ; Resources ; Software ; Supervision ; Validation ; Visualization ; Writing – original draft (Supporting); Writing – review & editing (Supporting). Laila Benzekri: Conceptualization ; Data curation ; Formal analysis ; Investigation ; Methodology ; Project administration ; Resources ; Software ; Supervision ; Validation ; Visualization ; Writing – original draft (Supporting); Writing – review & editing (Supporting). Karima Senouci: Conceptualization ; Data curation ; Formal analysis ; Investigation ; Methodology ; Project administration ; Resources ; Software ; Supervision ; Validation ; Visualization ; Writing – original draft (Supporting); Writing – review & editing (Supporting).The patients' caregivers in this manuscript have given written informed consent to the publication of their case details.


The disposal of tires at the end of their lifespan results in societal and environmental issues. To tackle this, recycling and reuse are effective solutions. Among various recycling methods, devulcanization is considered to be a very sustainable option, as it involves the controlled breakdown of crosslinks while maintaining the polymer backbones. The objective of this study is to develop a sustainable devulcanization process for passenger car tire rubber using silanes. In this study, a thermo-mechanical–chemical devulcanization process was conducted to screen six potential devulcanization aids (DAs). Silanes were chosen as they are widely used in tire rubber as coupling agents for silica. The efficiency of the devulcanization was studied by the degree of network breakdown, miscibility of the devulcanized material, and mechanical properties of the de- and revulcanized material. Compared to the parent compound, a 55–60% network breakdown was achieved for the devulcanizate along with 50–55% of tensile strength recovery. In addition to superior devulcanization efficiency, this DA offers a sustainable alternative to the conventional ones, such as di-phenyl-di-sulphide, due to its compliance with safety regulations. The devulcanizate can be utilized in high-performance applications, such as tires and seals, while 100% devulcanizate can be employed in low-strength technical rubber products. The extensive usage of rubber in various fields of application causes a serious environmental problem in terms of waste. In this scenario, the great challenge for civilization is to recycle and reuse this rubber . Around Landfilling of end-of-life tires (ELTs) is inhibited in the European Commission since 1999, which accelerated the recycling and reuse of ELTs in many European countries . Most ofDifferent recycling methods for rubber are described in the literature ,8, namelThe most common and effective devulcanization mechanism is the rearrangement of the covalent bonds. Devulcanization aids (DAs) produce free radicals or reactive moieties during the devulcanization process, which react with the active groups of the broken crosslinks and form a new stable bond. Disulphides are the most common moieties for devulcanization, e.g., bis(3-triethoxysilyl propyl) disulphide (TESPD), diphenyl disulphide (DPDS), 2,2-dibenzamido-diphenyl disulphide (DBDPD), etc. . A DA coThe filler system plays a vital role in the devulcanization process, as filler–polymer and filler–filler bonds become distorted during the thermo-mechanical process. For natural rubber (NR) filled with carbon black (CB), devulcanization is comparatively easier than for silica-filled rubbers: the breakdown of the physical interaction between the filler and polymer matrix is easier than the breakdown of the chemical bonds . In tireIn this study, different silane-based DAs are screened and the devulcanizates are analyzed by the degree of network breakdown, mechanical properties of the revulcanized material, and miscibility of the devulcanized rubber with a virgin compound. The process can be described as the devulcanization of crosslinked polystyrene and polybutadiene rubbers reinforced by a silica–silane system. A silica-filled SBR-BR-based model tire tread compound was used as the feed material for the devulcanization process. Commercially available silane coupling agents with disulphide, polysulphide, amino, alkenyl, and mercapto moieties were selected as DAs for the screening trials. The DAs are selected considering the potentially active chemical moieties and processibility for devulcanization. Moreover, sustainability, environmental and health impacts, EU safety regulations, innovation, and commercial feasibility are considered for this development.Preparation of the model compound.Devulcanization.Characterization.The experimental process can be classified into three parts:A brief description of each component of the experimental process is described below and the flowchart is shown in 2/s and at 100 °C it was 18.4 mm2/s. The different stages of the model compound preparation are described below.A SBR-BR-based silica-filled model tire tread compound was prepared as feed material for the devulcanization process. The kinetic viscosity of the TDAE oil at 40 °C was 331 mmThe model tire tread formulation is given in The list of the DAs for screening, reference DAs, and chemicals used for the characterization processes are described in Compounding was performed in two stages: the first step was performed in a 390 mL internal mixer (Model-350S) from Brabender GmbH & Co., Duisburg, Germany, followed by the final mixing on a lab scale two-roll mill (9 cm in diameter) of Schwabenthan GmbH & Co., Germany. The first step of mixing was conducted with a fill factor of 70%, initial temperature of 80 °C, and initial rotor speed of 70 rpm. During the initial step of the compounding process, the polymer underwent mastication to facilitate the incorporation of fillers and other compounding ingredients. As the temperature increased, the viscosity of the polymer decreased. Simultaneously, the addition of fillers led to an increase in viscosity. To ensure optimal reaction conditions for the silica–silane interaction, a temperature of 145 °C , known tThe masterbatch, the material produced after the first mixing step, was kept for one day at room temperature before final mixing. Then, the compound was kept again for one day at room temperature before curing.95 value. Compression molding was performed in an automatic press of Wickert Maschinenbau GmbH, Germany, with a 200 mm × 200 mm × 4 mm mold. After curing, the tensile strength of the vulcanized sheets was around 16 ± 1 MPa and the elongation at break was around 310 ± 30%.The optimum cure time was measured in a RPA Elite from TA Instruments, New Castle, DE, USA. The samples were cured at 160 °C according to the TChopping of the vulcanized sheets was performed with a bale cutter. The pre-treatment of the chopped samples was conducted by dipping them into liquid nitrogen for 4–5 min to achieve a temperature below the glass transition, followed by grinding at room temperature. Grinding was performed in a mechanical grinder from Fritsch, Germany, with a 0.7 mm mesh screen.The devulcanized rubber samples were compounded and revulcanized for measuring the stress–strain properties. The revulcanization formulation is shown in 95 value in an automatic compression molding machine from Wickert Maschinenbau GmbH, Germany.The compounded devulcanized rubber was tested in the RPA 2000 Elite of TA Instruments, New Castle, DE, USA, at 160 °C for 30 min according to ASTM D7750-12  to deterThe ground model tire tread rubber was the feed material for the devulcanization process. It was swollen with oil and DA before performing the devulcanization reaction. A brief description of the devulcanization process is given below.The rubber granulate was first mixed with the process oil and after that with the DA at room temperature. After each addition, the samples were kept for one day at room temperature for swelling. Due to the high viscosity of the process oil, the rubber granulate was mixed with oil and manually stirred. The oil-swollen sample was then re-swollen with the DA and kept for one day for the migration of the DA into the particles.The thermo-mechanical–chemical devulcanization process was performed in a Plastograph EC internal mixer with a volume of 50 cc from Brabender GmbH & Co., Germany. Non-intermeshing counter-rotating rotors and a telescopic ram were used. To minimize oxidation at high temperatures, the cavity was sealed with paraffin wax.A two-roll mill from Schwabenthan, GmbH & Co., Germany, with a 200 mm length × 80 mm diameter was used at room temperature, with a 1.25 speed ratio at 30 rpm for the milling of the devulcanized rubber. The nip gap was reduced gradually from 1 to 0.1 mm, and the devulcanized rubber formed a band.According to pre-trial data, the variable and constant process conditions for the devulcanization were selected. For the reference sample, DPDS (diphenyl disulphide) and DBD (2-2′-dibenzamido-diphenyl disulphide) were used as DAs and processed according to the conditions obtained from the literature . The samThe characterization process consisted of three parts: degree of devulcanization as deducted from the HorikxVerbruggen plot, stress–strain properties in tensile mode, and white rubber analysis.ASTM D 6814-02  describer) was determined using the additivity rule of volumes as given in Equation (1) [r is the weight of the rubber specimen, Ws is the weight of the absorbed solvent, ρr is the density of the rubber, and ρs is the density of the solvent. The apparent crosslink density (Vc) was calculated according to Flory–Rehner using Equation (2) [r is the volume fraction of the polymer in the swollen specimen, χ is the Flory–Huggins polymer–solvent interaction parameter, Mc is the molecular weight between crosslinks, and Vs is the molar volume of the solvent. For the SBR–toluene system [s) and the density values of toluene were 106.2 cm3/mol and 0.866 g/cm3, respectively. The percentage of network breakdown was calculated according to Equation (3) [c1 and Vc2 are the crosslink densities of the samples before and after devulcanization, respectively [The samples were then swollen in toluene at room temperature for 72 h, according to the ASTM standard. The volume fraction of the sample in the swollen gel (Vtion (1) :(1)Vr=Wrtion (2) :(2) Vc=1e system , the valtion (3) ,37:(3) Nectively ,36,37.apparent is the measured crosslink density according to the Flory–Rehner equation and Vactual is the actual crosslink density after correction for the filler. k is a constant for a given filler, Φ is the volume fraction of the filler in the specimen, Wb is the weight of the specimen before extraction, and Wa is the weight of the specimen after the extraction of all soluble material, such as polymer sol fraction, oil, and soluble chemical residues [The crosslink density according to the Flory–Rehner equation was not the actual one in a filled compound. To determine the exact crosslink density, the Kraus correction was applied.residues ,37.Considering the sol fraction of the feed material, the limiting lines of the random scission and crosslink scission were calculated according to the Horikx–Verbruggen method . PlottinIn Stress–strain properties of the revulcanized rubber were measured with a Z010 tensile tester manufactured by Zwick Roell GmbH & Co., Germany, according to ASTM D412 . For eacAfter the devulcanization process, there may still be undevulcanized particle cores in the devulcanizate. Devulcanized polymer chains are homogeneously miscible with a compatible polymer or compound; however, undevulcanized particle cores are not under the same conditions. Considering this, it is important to analyze the number, size, and total area of these undevulcanized particle cores. For this purpose, white rubber analysis (WRA) was developed. In this quantitative analytical method, the devulcanizate was blended with a bright-white polybutadiene-based compound colored with titanium dioxide. The white colorant was judiciously selected to create a high contrast between the background and devulcanizate, which led to a quantitative characterization process.White rubber compounds are polybutadiene and titanium dioxide based. The samples were prepared by mixing 10% devulcanizate into this white rubber compound. This resulted in a gray compound, in which the remaining non-devulcanized particles were visible as brownish spots. The digital analysis of the particles and particle size distribution was performed using a VHX 5000 digital microscope from Keyence.2 and 30% O2, with the same flow rate and ramp speed, from 600 °C to 900 °C. Equilibration was performed at three different temperatures, namely, 30 °C, 600 °C, and 900 °C, each for a duration of five minutes.Thermogravimetric Analysis (TGA) was performed using a TGA 550 instrument, supplied by TA Instruments, New Castle, DE, USA. The test was conducted in a nitrogen atmosphere with a flow rate of 50 mL/min, ramp speed of 10 °C/min, and ranging from 30 °C to 600 °C. Subsequently, the test was continued in an air atmosphere comprising 70% NThis part was classified into the three main properties: degree of network breakdown, stress–strain properties, and homogeneity. Finally, the reaction mechanism was elucidated.In With PS, the network breakdown percentage increased from 25% to 40% with an increasing residence time of 4 to 6 min, for a devulcanization temperature of 140 °C. When the temperature was increased to 160 °C at a residence time of 6 min, the sol content increased from 6% to 10% and the network breakdown percentage increased to 53%. The breaking of the crosslinks and reaction with the DA to hamper the recombination and to form sulphur–silane bonds was a probable reason for the higher degree of devulcanization. For the samples devulcanized with DS, AM, and ME, the data points were mostly close and above the random scission line. The points are on the left side of the graph, which indicates insufficient devulcanization of the granulate. It can be concluded that the di-sulphidic, mercapto, and amino moieties are less efficient than the alkenyl and polysulphide groups in this process window.Based on The comparative analysis of the tensile strength of the revulcanized samples is shown in A comparative analysis of the elongation at break values of the revulcanized samples is shown in From this screening, it can be concluded that VP resulted in the best stress–strain properties, followed by VN. Considering the tensile strength of the feed material, the tensile strength recovery was around 50–55%. This fits well with the findings of the network breakdown analysis: VP showed the best performance as DA.The homogeneity of the DA optimization trials was elaborated in the white rubber analysis. From the statistical analysis of the brownish devulcanizate dispersed in the white rubber matrix, the total number of visible particles and the particle size distribution were analyzed. The series of samples devulcanized at 160 °C for 6 min was selected. The comparative results for devulcanizates using different DAs are shown in For the samples devulcanized with VP or AM, the particle size distribution was on the finer side, and the total number of visible particles was higher than for all other samples. The samples devulcanized with DS, PS, VN, ME, and DPDS were comparatively coarser with a lower number of visible particles. This shift in the particle size distribution was an effect of the devulcanization efficiency and mechanical grinding processes.In The alkenyl silane with the activator presented the best performance within this group of potential DAs. From a mechanistic view, one of the reasons was the presence of the unsaturated carbon–carbon bond. The proposed reaction mechanism is that the alkenyl silane and polymer react and experience a chain-transfer reaction, in which the alkenyl moiety becomes attached to the broken crosslinks and restricts a further recombination, as shown in After the chain transfer, the molecule experiences a disproportion reaction to achieve greater chemical stability. The activator in the alkenyl silane improved the reactivity of the latter during devulcanization, as shown in ® was employed as a coupling agent to enhance silica reinforcement containing ethoxy groups. VN contains both ethoxy groups and carbon–carbon double bonds. The comparative peak intensities can provide an insight into the progression of the devulcanization reaction, as shown in The model compound used as the feed material for the devulcanization process contained carbon–carbon double bonds: the base polymers were unsaturated rubbers, such as SBR and BR. In the preparation of the model compound, Si 266−1 and 2917 cm−1, which corresponded to the C–H bending of the alkanes and alkenes. The devulcanization reaction did not typically result in the formation of new moieties in the final product; it was primarily a chain-transfer reaction. No other significant peaks were observed [In the devulcanizate, a reduction in the intensity was observed for the peaks at 2850 cmobserved .−1, corresponding to C–O stretching, was noted, indicating the involvement of this functional group in the devulcanization process. Additionally, a peak at 754 cm−1, associated with the C=C bending of alkene, was detected, signifying the reactivity of VN during devulcanization. These observations provide evidence of the reactivity and transformation of VN during the devulcanization process [In comparison to pure VN, several peaks disappeared in the devulcanized sample. A peak at 1166 cm process .The devulcanization efficiencies of the different silanes in terms of mechanical properties, network breakdown, and miscibility were comparatively analyzed in this study. The SBR-silica network is the main challenge for passenger car tire rubber devulcanization, and a potential solution was developed by using alkenyl silane as a devulcanization aid (DA). The efficiency of this silane as DA was further improved by the presence of an activator; this combination turned out to be the most promising DA for passenger car tire rubber devulcanization.Alkenyl silane and alkenyl silane with activator devulcanized samples showed the best mechanical and network breakdown properties, followed by the ones devulcanized with polysulphidic and amino silane. Compared to other silanes, the alkenyl and the variant with the activator showed a higher crosslink-to-random-scission ratio, resulting in a better devulcanizate quality. A greater extent of devulcanization in rubber leads to an increased number of free polymer chains, resulting in enhanced miscibility. Conversely, reduced devulcanization leads to a reduced presence of free polymer chains, resulting in decreased miscibility and an increased quantity of immiscible particles. A linear correlation was established between the devulcanizate quality in terms of tensile strength and the total area of visible, insufficiently devulcanized particles for all silane devulcanized samples.Considering the properties of the feed material, the recovery of the tensile strength was around 50–55%, and the network breakdown percentage was 55–60%: these are rather high percentages for an SBR–silica system due to the strong filler–polymer network. An optimization of the process parameters is required for the further improvement of the devulcanizate quality. A reaction mechanism was proposed; however, further research on and the analysis of the devulcanization process and reactions are required.


Significant concerns have been raised about a potential acceleration of trends in antimicrobial resistance (AMR) due to the COVID-19 pandemic. The pandemic disrupted infection control and antimicrobial stewardship processes and introduced a novel respiratory infection that mimics bacterial pneumonia, resulting in increases in hospital acquired infections and overall antibiotic prescribing. The objective of this study is to compare AMR of key bacterial pathogens before and during the pandemic to identify any concerning trends.Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE) and extended-spectrum beta-lactamase (ESBL). In addition to descriptive results, we assessed for statistically significant changes between pre and during-COVID using chi-square tests.We used bacterial culture data  from 313 U.S. hospitals in the Premier Healthcare Database to compare AMR patterns pre-COVID and during-COVID, defined as Jan. 2019 to Feb. 2020 and Mar. 2020 to Mar. 2022, respectively. We characterized % resistant cultures for three organisms identified as major threats to public health: methicillin-resistant There were 141,027 cultures analyzed for MRSA, 104,770 for VRE and 655,240 for ESBL. Wound was the most common culture type for MRSA (51.20%), while urine was most common for VRE and ESBL . Between pre and during-COVID, the percent of MRSA isolates decreased , VRE isolates increased , and ESBL infections decreased  (Table 1). There were differences in AMR across all pathogens by race (p < 0.001) and ethnicity (p < 0.001) both pre and during-COVID. Risk of AMR infections increased among Black and Hispanic patients during COVID (Table 2).Unexpectedly, we observed a statistically significant decrease in AMR for MRSA and ESBL during-COVID. AMR risk among racial and ethnic minority groups further increased during-COVID, raising concern about this as an additional area of disparity. The clinical significance of these results remains unclear and further research is needed to characterize the short and long term impact of COVID on AMR.All Authors: No reported disclosures