Diagnosis and follow-up of inborn errors of amino acid metabolism: Use of proton magnetic resonance of biological fluids

Summary Proton magnetic resonance spectra of biological fluids such as urine, plasma and cerebro-spinal fluid can be used for multi-component analysis of highly concentrated species, thus providing information about the general metabolism of the patient. Hydrogen containing analytes in concentration higher than 10µM are indeed often detectable in biological fluid in 15 minutes by means of an unexpensive 200 MHz spectrometer essentially without sample manipulation. Amino acids, keton bodies, organic acids and other metabolites can be easily estimated by this approach; consequently this technique represents a powerful tool particularly in the diagnosis of inborn errors of amino acid metabolism, when improving the prognosis often depends on a very early diagnosis and on an effective method for monitoring the effects of therapy.In the present paper, several cases of inherited diseases related to amino acid impaired metabolism will be presented to illustrate the importance in the diagnosis. Phenylketonuria, tyrosinemia, cystinuria, ornithinemia, argininosuccinic aciduria, maple syrup urine disease (MSUD), alkaptonuria, lysinuria and other genetic pathologies were in fact unambiguously and rapidly diagnosed by means of the identification in the biological fluids of the relevant accumulating amino acids and/or of their metabolites. The proposed technique is suitable to become, in the future, a useful routine tool for a wide neonatal screening.     

Mechanisms by which neonatal testosterone exposure mediates sex differences in impulsivity in prepubertal rats

Neonatal testosterone, either acting directly or through its conversion to estradiol, can exert organizational effects on the brain and behavior. The goal of the current study was to examine sex differences and determine the role of neonatal testosterone on prefrontal cortex-dependent impulsive choice behavior in prepubertal rats. Male and female prepubertal rats were tested on the delay-based impulsive choice task. Impulsive choice was defined as choosing an immediate small food reward over a delayed large reward. In a first experiment to examine sex differences, males made significantly more impulsive choices than did females. In a second experiment to examine the organizational effects of testosterone, females treated with neonatal testosterone made significantly more impulsive choices than did control females and their performance was indistinguishable from that of control males. In a third experiment to determine if the effect of testosterone on performance is due to the actions of androgens or estrogens through its conversion to estradiol, males treated neonatally with the aromatase inhibitor formestane, which blocks the conversion of testosterone to estradiol, females treated neonatally with the non-aromatizable androgen dihydrotestosterone, and females treated neonatally with estradiol made significantly more impulsive choices than did control females and their performance was indistinguishable from that of control males. Results indicate that male pubertal rats display increased impulsive choice behavior as compared to females, that this sex difference results from organizing actions of testosterone during the neonatal period, and that this effect can result from both androgenic and estrogenic actions.     

VIP-innervation of rat intestine: A developmental study with monoclonal antibodies

Four monoclonal antibodies to VIP have been generated and shown to be N-terminal specific with high affinity for VIP. VIP-containing nerve fibers and cell bodies were visible in the upper small intestine from day 1 of neonatal life. Initially the immunoreactivity was mostly in the myenteric plexus but extended into the sub-mucous plexus by day 7. From day 1 to day 7 the VIP-innervation developed both orally and caudally at a similar rate. In the stomach, the antrum showed sub-mucosal cell bodies by day 14, while in the corpus the cell bodies remained confined to the myenteric plexus. The colon showed positive fibers in the myenteric plexus at day 7 and cell bodies and fibers in the sub-mucous plexus by day 14. The size (cross-sectional area) of the individual VIP-immunoreactive cell bodies increased significantly between day 1 and day 14 with no further increase with age. At no time were immunoreactive cell bodies shown to migrate from the myenteric to the sub-mucous plexus. VIP-immunoreactive epithelial cells were not detected in the present study.     

The effect of cyclic adenosine 3′,5′-monophosphate on the uptake of estradiol by the neonatal mouse uterus

Summary Uterine tissue from neonatal mice was incubated in vitro at 0° C for 1 h in a medium containing 1×10^-8 M ³H-estradiol with or without 1×10^-4M dibutyryl cyclic AMP. In some incubations the temperature was raised to 37° C for 15 min after incubation in the cold, in others the temperature was kept at 0° C during this 15 min period. The tissue was frozen in liquid propane cooled in liquid nitrogen, sectioned at 2 or 4 microns, and autoradiograms prepared according to the dry-mount procedure. cAMP increases the cellular uptake of ³H-estradiol in uterine tissue. After rising the temperature to 37° C, grains appeared over the nuclei. cAMP at low temperature increased the cellular uptake of ³H-estradiol, but the grains were not associated with the nuclei. In the autoradiograms the grain number above the epithelium was markedly less than above the stroma.This work has been supported by grants from the Norwegian Research Council for Science and the Humanities, and from the Norwegian Cancer Society (Landsforeningen mot Kreft)     

Crigler-Najjar syndrome type 2: Novel UGT1A1 mutation

Crigler-Najjar syndrome type 2 is a rare cause for persistent unconjugated hyperbilirubinemia, inherited in an autosomal recessive manner. Even though it is compatible with normal life span, in the absence of prompt suspicion and intensive management it can prove fatal not only in the neonatal period but also during adult life. Here, we describe a case with a novel homozygous UGT1A1 p.Pro176Leu mutation.     

Costos directos de la infección adquirida en la comunidad por neonatos a término con bajo riesgo al nacer,Cundinamarca, Colombia

IntroducciónEl 50% de los episodios de sepsis neonatal se originan en la comunidad, con un gran porcentaje de mortalidad y complicaciones.ObjetivoEstimar los costos directos de la hospitalización por infección neonatal adquirida en la comunidad en neonatos a término con bajo riesgo al nacer.Materiales y métodosSe utilizó la perspectiva del tercer pagador y la técnica de microcosteo; el horizonte de tiempo fue la duración de la hospitalización. La determinación de las situaciones generadoras de costos se obtuvo por medio de un consenso de expertos y se cuantificaron con base en la factura detallada de la atención de 337 neonatos hospitalizados. Los costos de los medicamentos se calcularon con base en el Sistema de Información de Precios de Medicamentos (SISMED) y, el de los procedimientos, según los manuales tarifarios ISS 2001 con porcentaje de ajuste y el seguro obligatorio de accidentes de tráfico (SOAT). Para incorporar la variabilidad de la información en la estimación, se obtuvo una distribución de los costos usando el método de bootstrapping.ResultadosSe incluyeron las facturas por la atención de 337 recién nacidos. El promedio de costos directos de la atención por paciente fue de COL$ 2’773.965 (desviación estándar, DE=$ 198.813,5; IC_95%: $ 2’384.298 - $ 3’163.632). Las principales categorías generadoras de costos fueron la internación en la unidad de cuidados intensivos y las tecnologías en salud. Los costos siguieron una una distribución logarítmica normal (log-normal).ConclusionesLas categorías con mayor impacto en los costos fueron la internación en la unidad neonatal y las tecnologías en salud. Los costos se ajustaron a una distribución logarítmica normal.Palabras clave: sepsis neonatal, costos y análisis de costo, recién nacido, unidades de cuidado intensivo neonatal, mortalidad infantil     

Significant hepatic expression of IL-2 and IL-8 in biliary atresia compared with other neonatal cholestatic disorders

ObjectivesAlthough the exact etiology of biliary atresia (BA) is still elusive, inflammation plays a key role. Release of proinflammatory cytokines from activated immune cells perpetuates the injury and causes biliary destruction. We aimed to study interleukin (IL)-2 and IL-8 expression in liver tissue of BA patients compared with other neonatal cholestatic disorders.MethodsThe study included 59 infants with neonatal cholestasis in two groups; BA group (n = 31) and non-BA group (n = 28) with cholestatic disorders other than BA as controls. Demographic, clinical, laboratory, and histopathological parameters were collected. IL-2 and IL-8 immunostaining was performed. Immunostaining in portal cellular infiltrate was scored as positive or negative and expressed as the mean cell count in three portal tracts.ResultsThe mean value of IL-2 and IL-8 positive inflammatory cells was significantly higher in BA than in non-BA group (P-values of 0.004 and 0.002 respectively). IL-2 correlated significantly with IL-8 immunostaining in both BA and non-BA group (P < 0.0001 for both). Furthermore, both cytokines in both groups correlated significantly with inflammatory activity in liver biopsy while there was no significant correlation with the other studied parameters. Yet, there was a trend of increased expression of IL-2 and IL-8 with increasing stage of fibrosis in BA group. This trend was not observed in non-BA group.ConclusionThe significantly higher expression of IL-2 and IL-8 in patients with BA compared to non-BA suggests a potential role for these cytokines in the pathogenesis in therapy of this devastating neonatal hepatic disorder.     

皮胆红素百分位曲线图结合相关风险因素预测新生儿高胆红素血症的临床价值

摘要 目的：评价新生儿出生后72 h经皮胆红素（TcB）百分位曲线图结合临床相关风险因素，预测新生儿高胆红素血症的发生情况。方法：选择2018年1月-2019年12月在安徽理工大学第一附属医院出生的晚期早产儿和足月儿，使用经皮黄疸仪监测其黄疸值，绘制TcB百分位列线图，以新生儿出生后72 h内末次TcB值对应的风险区结合致病风险因素预测新生儿高胆红素血症发生的价值。结果：3818例新生儿出生后72 h后高危区人数为278例（7.28%）。TcB数值在4 h到48 h内上升最快，峰值出现在出生后84 h-120 h，P40、P75及P95峰值分别为193.75 μmol/L，224.75 μmol/L和282.25 μmol/L，其中P95峰值出现最晚。新生儿出生后0-48 h内共计有244例TcB值处于高危险区，其中92例在72 h后仍处高危区，预测灵敏度为29.97%，特异度为95.67%；49-72 h内共计有269例新生儿TcB值处于高危区，其中116例新生儿在72 h后TcB值仍处高危区，灵敏度为36.48%，特异度为95.62%。多因素Logistic回归分析显示，相关致病危险因素有：胎龄、住院时间、分娩方式、胎膜早破及喂养方式（P<0.05）。72 h内TcB危险区的受试者工作特征（ROC）曲线下面积为0.75（95%CI:0.56-0.93），结合相关风险因素的ROC曲线下面积为0.93（95%CI:0.81-1.00），预测价值明显提高。结论：TcB百分位曲线图结合"高危因素"预测新生儿高胆红素血症准确性较高，操作简便，具有较好的临床价值。     

Neonatal size and infant mortality at high altitude in the western Himalaya

A prospective study was undertaken in Ladakh, India, a high-altitude region of the Himalaya, to investigate the effects of small average birth size on neonatal mortality. While such studies exist from high-altitude regions of the New World and shed light on the adaptive status of high-altitude-dwelling populations there, this is the first to examine this relationship in the Himalaya. In a sample of 168 newborns, birthweight and other anthropometric measurements were reduced relative to Andean and Tibetan newborns. Logistic regression and hazard analysis showed that neonatal biological characteristics such as weight, fatness, and circumferences were important predictors of survival probabilities of infants, especially in the neonatal period. Low Rohrer's Ponderal Index (PI) was particularly strongly related to poor survival outcome. Males and females showed no significant differences in mortality risk. Data derived from reproductive histories revealed that neonatal mortality accounted for 70–80% of total infant mortality in Ladakh. Compared to other high-altitude studies, small newborn size in Ladakh was associated with much higher mortality risks; mortality risk rose dramatically with birthweights below the mean (2,764 grams), which characterized 50% of all newborns. It is argued that newborns in Ladakh are subject to strong directional selective forces that favor higher birthweights that incur lower risks of neonatal mortality, while Andean infants are subject to relatively mild selection pressure at both ends of the birthweight distribution. Given the overall small size at birth of Ladakhi newborns and the poor survival outcomes of newborns below the mean, it is suggested that this population is less well adapted in a biological sense to the stresses inherent in this high-altitude environment than are Andean populations, perhaps due to the relatively recent colonization of the area and the substantial genetic admixture that has occurred in the past. © 1994 Wiley-Liss, Inc.     

Toward in vitro-to-in vivo translation of monoclonal antibody pharmacokinetics: Application of a neonatal Fc receptor-mediated transcytosis assay to understand the interplaying clearance mechanisms

Monoclonal antibodies (mAbs) are a rapidly growing drug class for which great efforts have been made to optimize certain molecular features to achieve the desired pharmacokinetic (PK) properties. One approach is to engineer the interactions of the mAb with the neonatal Fc receptor (FcRn) by introducing specific amino acid sequence mutations, and to assess their effect on the PK profile with in vivo studies. Indeed, FcRn protects mAbs from intracellular degradation, thereby prolongs antibody circulation time in plasma and modulates its systemic clearance. To allow more efficient and focused mAb optimization, in vitro input that helps to identify and quantitatively predict the contribution of different processes driving non-target mediated mAb clearance in vivo and supporting translational PK modeling activities is essential. With this aim, we evaluated the applicability and in vivo-relevance of an in vitro cellular FcRn-mediated transcytosis assay to explain the PK behavior of 25 mAbs in rat or monkey. The assay was able to capture species-specific differences in IgG-FcRn interactions and overall correctly ranked Fc mutants according to their in vivo clearance. However, it could not explain the PK behavior of all tested IgGs, indicating that mAb disposition in vivo is a complex interplay of additional processes besides the FcRn interaction. Overall, the transcytosis assay was considered suitable to rank mAb candidates for their FcRn-mediated clearance component before extensive in vivo testing, and represents a first step toward a multi-factorial in vivo clearance prediction approach based on in vitro data.