Monitoring of cerebral oxygenation, cerebrovascular reactivity and circulatory function in preterm infants

Monitoring of cerebral oxygenation, cerebrovascular reactivity and circulatory function in preterm infants Brain injury in the preterm infant is associated with death and lifelong disability. Cerebral hypoxia and fluctuations in cerebral blood flow in the first two days of life have been implicated in the pathophysiology of haemorrhagic and ischaemic brain injury. Monitoring of haemodynamic changes during the early transitional circulation from in-utero to ex-utero life are currently based on standard measurements of systemic oxygenation and mean arterial blood pressure, with no reliable assessment of end-organ perfusion. In this thesis, measurements using near-infrared spectroscopy (NIRS) and functional echocardiography were made to assess cerebral perfusion and systemic blood flow in a cohort of preterm infants undergoing intensive care. This thesis is divided into four sections: i) The feasibility of continuous monitoring of cerebral oxygenation and cerebrovascular reactivity is demonstrated in a series of case reviews, and the association between cerebral oxygenation and cerebrovascular reactivity with outcome of brain injury and mortality is described. ii) Combining measurements of systemic blood flow with end organ perfusion was applied to define MABPOPT in preterm infants based on an index of cerebrovascular reactivity. Deviations below MABPOPT were associated with intraventricular haemorrhage and mortality. iii) The complexity of brain and systemic signals was studied by using multi-scale entropy analysis. Most studies using cerebral NIRS or systemic measurements of blood flow use linear analysis; however, a complex biological system, such as the human brain, includes many regulatory mechanisms that interact in a complex manner, resulting in effects that cannot be understood wholly through the analysis of its individual constituents. Lower complexity of brain signals was observed in infants who developed intraventricular hemorrhage or died. iv) Changes in systemic and cerebral oxygenation in a cohort of preterm infants in the first 48 hours of life was assessed using functional echocardiography. The patterns of changes in cardiac output and cerebral oxygenation in infants who did and did not have intraventricular haemorrhage are discussed. Furthermore, the relationship between the presence of a haemodynamically significant ductus arteriosus and brain injury is assessed.Cambridge Overseas Trust & Capes Scholarshi

Evaluation of ELISA procedures to detect von Willebrand Factor with monoclonal antibodies

The von Willebrand Factor is a multimeric glycoprotein responsible for the promotion of platelet adhesion and aggregation at sites of vascular injury, and for FVIII stabilization. Abnormalities on this protein are responsible for diverse types of von Willebrand Disease. In the present study, monoclonal antibodies against human von Willebrand Factor were developed as a means to improve von Willebrand Disease research and diagnosis. Monoclonal antibodies were tested for their ability to bind to purified and plasmatic von Willebrand Factor. Monoclonal antibodies vW22 and vW23 were found to bind only purified von Willebrand Factor, and monoclonal antibodies vW18 and vW21 were found to bind purified and plasmatic von Willebrand Factor. Antibodies vW18 and vW21 were used to perform a sandwich-enzyme-linked immunosorbent assay to detect and quantify von Willebrand Factor concentration in plasma samples from 143 coagulopathy patients and 12 healthy blood donors. The assay showed high performance, with strong correlation and agreement in results, when compared to electroimmunoassay (Rs = 0.843 and K = 0.691 with p<0.001) and a commercial ELISA (Rs = 0.930 and K = 0.819 with p<0.001). S-ELISA proved to be a useful tool in vWF quantification tests in Brazilian specialized laboratories as an alternative to imported tests.(Avaliação de procedimentos ELISA para detectar o Fator von Willebrand com anticorpos monoclonais). O Fator von Willebrand é uma glicoproteína multimérica responsável pela promoção da adesão e agregação de plaquetas nos locais de lesão vascular e pela estabilização do FVIII. Anormalidades na função ou estrutura desta proteína são responsáveis por diversos tipos de doença de von Willebrand. Para auxiliar na pesquisa e diagnóstico da doença de von Willebrand, este estudo desenvolveu anticorpos monoclonais contra fator von Willebrand humano. Os anticorpos monoclonais foram testados quanto à sua capacidade de se ligar ao fator von Willebrand purificado e plasmático. Os anticorpos monoclonais vW22 e vW23 ligaram-se somente ao fator von Willebrand purificado, e anticorpos monoclonais vW18 e vW21 ligaram-se tanto ao fator von Willebrand purificado como ao plasmático. Anticorpos vW18 e vW21 foram utilizados no desenvolvimento de um ELISA sandwich para detectar e quantificar a concentração de fator von Willebrand no plasma em uma amostra de 143 pacientes com coagulopatias e 12 doadores de sangue saudáveis. O teste mostrou alto desempenho, com forte correlação e concordância quando comparado com uma imunoeletrofose (Rs = 0,843 e K = 0,691 p <0,001) e um ELISA comercial (Rs = 0,930 e K = 0,819 p <0,001). O ELISA-S desenvolvido no presente trabalho mostrou um bom desempenho para ser usado como teste de quantificação vWF em laboratórios especializados no Brasil como alternativa para testes importados

Post-haemorrhagic hydrocephalus is associated with poorer surgical and neurodevelopmental sequelae than other causes of infant hydrocephalus.

PURPOSE: This retrospective cohort study aimed to investigate the surgical and neurodevelopmental outcomes (NDO) of infant hydrocephalus. We also sought to determine whether these outcomes are disproportionately poorer in post-haemorrhagic hydrocephalus (PHH) compared to other causes of infant hydrocephalus. METHODS: A review of all infants with hydrocephalus who had ventriculoperitoneal (VP) shunts inserted at Great Ormond Street Hospital (GOSH) from 2008 to 2018 was performed. Demographic, surgical, neurodevelopmental, and other clinical data extracted from electronic patient notes were analysed by aetiology. Shunt survival, NDO, cerebral palsy (CP), epilepsy, speech delay, education, behavioural disorders, endocrine dysfunction, and mortality were evaluated. RESULTS: A total of 323 infants with median gestational age of 37.0 (23.29-42.14) weeks and birthweight of 2640 g (525-4684 g) were evaluated. PHH was the most common aetiology (31.9%) and was associated with significantly higher 5-year shunt revision rates, revisions beyond a year, and median number of revisions than congenital or "other" hydrocephalus (all p < 0.02). Cox regression demonstrated poorest shunt survival in PHH, related to gestational age at birth and corrected age at shunt insertion. PHH also had the highest rate of severe disabilities, increasing with age to 65.0% at 10 years, as well as the highest CP rate; only genetic hydrocephalus had significantly higher endocrine dysfunction (p = 0.01) and mortality rates (p = 0.04). CONCLUSIONS: Infants with PHH have poorer surgical and NDO compared to all other aetiologies, except genetic hydrocephalus. Research into measures of reducing neurodisability following PHH is urgently required. Long-term follow-up is essential to optimise support and outcomes

Non-linear Dynamical Analysis of Intraspinal Pressure Signal Predicts Outcome After Spinal Cord Injury.

The injured spinal cord is a complex system influenced by many local and systemic factors that interact over many timescales. To help guide clinical management, we developed a technique that monitors intraspinal pressure from the injury site in patients with acute, severe traumatic spinal cord injuries. Here, we hypothesize that spinal cord injury alters the complex dynamics of the intraspinal pressure signal quantified by computing hourly the detrended fluctuation exponent alpha, multiscale entropy, and maximal Lyapunov exponent lambda. 49 patients with severe traumatic spinal cord injuries were monitored within 72 h of injury for 5 days on average to produce 5,941 h of intraspinal pressure data. We computed the spinal cord perfusion pressure as mean arterial pressure minus intraspinal pressure and the vascular pressure reactivity index as the running correlation coefficient between intraspinal pressure and arterial blood pressure. Mean patient follow-up was 17 months. We show that alpha values are greater than 0.5, which indicates that the intraspinal pressure signal is fractal. As alpha increases, intraspinal pressure decreases and spinal cord perfusion pressure increases with negative correlation between the vascular pressure reactivity index vs. alpha. Thus, secondary insults to the injured cord disrupt intraspinal pressure fractality. Our analysis shows that high intraspinal pressure, low spinal cord perfusion pressure, and impaired pressure reactivity strongly correlate with reduced multi-scale entropy, supporting the notion that secondary insults to the injured cord cause de-complexification of the intraspinal pressure signal, which may render the cord less adaptable to external changes. Healthy physiological systems are characterized by edge of chaos dynamics. We found negative correlations between the percentage of hours with edge of chaos dynamics (-0.01 ≤ lambda ≤ 0.01) vs. high intraspinal pressure and vs. low spinal cord perfusion pressure; these findings suggest that secondary insults render the intraspinal pressure more regular or chaotic. In a multivariate logistic regression model, better neurological status on admission, higher intraspinal pressure multi-scale entropy and more frequent edge of chaos intraspinal pressure dynamics predict long-term functional improvement. We conclude that spinal cord injury is associated with marked changes in non-linear intraspinal pressure metrics that carry prognostic information

Validation of molecular markers associated to leaf rust resistance genes in wheat

O objetivo deste trabalho foi validar marcadores moleculares previamente associados a genes que conferem resistência à ferrugem-da-folha, em genótipos brasileiros de trigo. Cinco marcadores STS e SCAR, identifi cados como associados aos alelos de resistência dos genes Lr1, Lr9, Lr10 e Lr24, foram avaliados por PCR, em 25 genótipos de trigo com conhecida presença ou ausência desses alelos. O marcador STS, associado ao alelo de resistência do gene Lr1, não foi efi ciente em identifi car genótipos brasileiros que possuem este alelo de resistência. Os marcadores STS e SCAR, associados a Lr9, Lr10 e Lr24, foram efi cientes na identifi caçãode plantas que possuem o alelo de resistência desses genes, e podem ser utilizados na seleção por marcadores da resistência à ferrugem-da-folha, em genótipos brasileiros de trigo.The objective of this work was to validate molecular markers previously associated to leaf rust resistance genes in Brazilian wheat genotypes. Five STS and SCAR markers identifi ed as associated to theresistance alleles of the genes Lr1, Lr9, Lr10 and Lr24 were tested by PCR in 25 Brazilian wheat genotypes with known presence or absence of these alleles. The STS marker associated to Lr1 was not effi cient in identifyingBrazilian genotypes carrying its resistance allele. The STS and SCAR markers associated to Lr9, Lr10 and Lr24 are effi cient in identifying plants carrying the resistance alleles for these genes, and therefore, can be usedfor marker-assisted selection of leaf rust resistance in Brazilian wheat genotypes

Validação de marcadores moleculares associados a genes de resistência à ferrugem-da-folha do trigo

The objective of this work was to validate molecular markers previously associated to leaf rust resistance genes in Brazilian wheat genotypes. Five STS and SCAR markers identifi ed as associated to theresistance alleles of the genes Lr1, Lr9, Lr10 and Lr24 were tested by PCR in 25 Brazilian wheat genotypes with known presence or absence of these alleles. The STS marker associated to Lr1 was not effi cient in identifyingBrazilian genotypes carrying its resistance allele. The STS and SCAR markers associated to Lr9, Lr10 and Lr24 are effi cient in identifying plants carrying the resistance alleles for these genes, and therefore, can be usedfor marker-assisted selection of leaf rust resistance in Brazilian wheat genotypes.O objetivo deste trabalho foi validar marcadores moleculares previamente associados a genes que conferem resistência à ferrugem-da-folha, em genótipos brasileiros de trigo. Cinco marcadores STS e SCAR, identifi cados como associados aos alelos de resistência dos genes Lr1, Lr9, Lr10 e Lr24, foram avaliados por PCR, em 25 genótipos de trigo com conhecida presença ou ausência desses alelos. O marcador STS, associado ao alelo de resistência do gene Lr1, não foi efi ciente em identifi car genótipos brasileiros que possuem este alelo de resistência. Os marcadores STS e SCAR, associados a Lr9, Lr10 e Lr24, foram efi cientes na identifi caçãode plantas que possuem o alelo de resistência desses genes, e podem ser utilizados na seleção por marcadores da resistência à ferrugem-da-folha, em genótipos brasileiros de trigo

Antigenic and molecular characterization of eight samples of Aujeszky's disease virus isolated in the state of Rio Grande do Sul, Brazil, in 2003

Pseudorabies or Aujeszky's disease (AD), caused by pseudorabies virus (PRV) is a major concern in swine production. In the state of Rio Grande do Sul, Brazil, AD was only detected in 1954, in cattle. In 2003 two outbreaks of encephalitis occurred on the northern region of the state, close to the border with the state of Santa Catarina. Pseudorabies virus (PRV) was isolated from distinct farms within the region and subjected to antigenic and genomic analyses. These isolates were compared with prototype strains NIA-3 and NP. Antigenic characterization with a panel of monoclonal antibodies (Mabs) directed to viral glycoproteins (gB, gC, gD and gE-,) was performed by an imunoperoxidase monolayer assay (IPMA) on infected cell monolayers. Genomic characterization was carried out by restriction enzyme analysis (REA) of the whole DNA viral genome with Bam HI. The antigenic profile of the eight isolates from Rio Grande do Sul as well as strains NIA-3 and NP were similar. REA analysis revealed that all isolates from Rio Grande do Sul displayed a genomic type II arrangement, a genotype often found in other outbreaks of AD previously reported in other Brazilian states. The results obtained suggest that the eight isolates examined here were similar