Mechanism of high-mannose N-glycan breakdown and metabolism by Bifidobacterium longum.

Bifidobacteria are early colonizers of the human gut and play central roles in human health and metabolism. To thrive in this competitive niche, these bacteria evolved the capacity to use complex carbohydrates, including mammalian N-glycans. Herein, we elucidated pivotal biochemical steps involved in high-mannose N-glycan utilization by Bifidobacterium longum. After N-glycan release by an endo-ß-N-acetylglucosaminidase, the mannosyl arms are trimmed by the cooperative action of three functionally distinct glycoside hydrolase 38 (GH38) α-mannosidases and a specific GH125 α-1,6-mannosidase. High-resolution cryo-electron microscopy structures revealed that bifidobacterial GH38 α-mannosidases form homotetramers, with the N-terminal jelly roll domain contributing to substrate selectivity. Additionally, an α-glucosidase enables the processing of monoglucosylated N-glycans. Notably, the main degradation product, mannose, is isomerized into fructose before phosphorylation, an unconventional metabolic route connecting it to the bifid shunt pathway. These findings shed light on key molecular mechanisms used by bifidobacteria to use high-mannose N-glycans, a perennial carbon and energy source in the intestinal lumen.

Structure optimization of lipopeptide assemblies for aldol reactions in an aqueous medium.

Four amphiphilic peptides were synthesized, characterized, and evaluated regarding their efficiency in the catalysis of direct aldol reactions in water. The lipopeptides differ by having a double lipid chain and a guanidinium pyrrole group functionalizing one Lys side chain. All the samples are composed of the amino acids l-proline (P), l-arginine (R), or l-lysine (K) functionalized with the cationic guanidiniocarbonyl pyrrole unit (GCP), l-tryptophan (W), and l-glycine (G), covalently linked to one or two long aliphatic chains, leading to surfactant-like designs with controlled proline protonation state and different stereoselectivity. Critical aggregation concentrations (cac) were higher in the presence of the GCP group, suggesting that self-assembly depends on charge distribution along the peptide backbone. Cryogenic Transmission Electron Microscopy (Cryo-TEM) and Small Angle X-ray Scattering (SAXS) showed a rich polymorphism including spherical, cylindrical, and bilayer structures. Molecular dynamics simulations performed to assess the lipopeptide polymorphs revealed an excellent agreement with core-shell arrangements derived from SAXS data and provided an atomistic view of the changes incurred by modifying head groups and lipid chains. The resulting nanostructures behaved as excellent catalysts for aldol condensation reactions, in which superior conversions (>99%), high diastereoselectivities (ds = 94 : 6), and enantioselectivities (ee = 92%) were obtained. Our findings contribute to elucidate the effect of nanoscale organization of lipopeptide assemblies in the catalysis of aldol reactions in an aqueous environment.

Folate status in women of childbearing age in the Urban Metropolitan Region of Chile: results from the National Health Survey 2016-2017.

OBJECTIVE: To analyse serum folate levels in women of childbearing age in the Metropolitan Region (MR) of Chile. DESIGN: Cross-sectional design as part of the 2016-2017 National Health Survey (Encuesta Nacional de Salud, ENS 2016-2017), using a household-based multistage stratified random sample. Serum folate levels measured by electrochemiluminescence immunoassay in fasting venous blood samples were classified as deficient (<4·4 ng/ml), normal (4·4-20 ng/ml) or supraphysiological (>20 ng/ml). SETTING: The MR of Chile. PARTICIPANTS: Women of reproductive age (15-49 years, n 222) from the MR participated in the ENS 2016-2017. RESULTS: The mean, median and range of serum folate were 14·2 (se 0·4), 13·9 and 2·1-32·2 ng/ml, respectively. Folate deficiency was detected in 0·9 % of women, while 7·0 % had supraphysiological levels of the vitamin. No significant effects of age, educational level, marital status, parity, smoking status or nutritional status on serum folate levels were detected by univariate or multivariate analyses. Intake of folic acid supplements showed a significant association with serum folate levels, but only 1·2 % of women used supplements. CONCLUSIONS: Folate deficiency in women of reproductive age living in the MR of Chile is almost inexistent according to the ENS 2016-2017, suggesting that the current population-wide mandatory folic acid fortification of flour is an effective and equitable measure to prevent folate deficiency. These results support the option of maintaining current folic acid fortification in Chile, particularly based on the low adherence to supplementation regimes evidenced in other populations.

Nanoparticles containing ß-cyclodextrin potentially useful for the treatment of Niemann-Pick C.

ß-Cyclodextrin (ß-CD) is being considered a promising therapy for Niemann-Pick C (NPC) disease because of its ability to mobilise the entrapped cholesterol from lysosomes, however, a major limitation is its inability to cross the blood-brain barrier (BBB) and address the central nervous system (CNS) manifestations of the disease. Considering this, we aimed to design nanoparticles able to cross the BBB and deliver ß-CD into the CNS lysosomes. The physicochemical characteristics of ß-CD-loaded nanoparticles were evaluated by dynamic light scattering, small-angle X-ray scattering, and cryogenic transmission electron microscopy. The in vitro analyses were performed with NPC dermal fibroblasts and the ß-CD-loaded nanoparticles were tracked in vivo. The nanoparticles showed a mean diameter around 120 nm with a disordered bicontinuous inner structure. The nanoparticles did not cause decrease in cell viability, impairment in the antioxidant enzymes activity, damage to biomolecules or release of reactive species in NPC dermal fibroblasts; also, they did not induce genotoxicity or alter the mitochondrial function in healthy fibroblasts. The ß-CD-loaded nanoparticles were taken up by lysosomes reducing the cholesterol accumulated in NPC fibroblasts and reached the CNS of mice more intensely than other organs, demonstrating advantages compared to the free ß-CD. The results demonstrated the potential of the ß-CD-loaded nanoparticles in reducing the brain impairment of NPC.

Early origins of allergy and asthma (ARIES): study protocol for a prospective prenatal birth cohort in Chile.

BACKGROUND: Growing evidence shows that atopic dermatitis (AD), food allergy (FA), allergic rhinitis, and asthma are largely determined during the first 1000 days (time elapsed from conception to the 2nd birthday). The ARIES birth cohort aims to determine prenatal and perinatal conditions, as well as genetic and epigenetic factors, that participate in the early setting of immune responses, and the role of these in the later determination of the risk of allergic diseases and asthma in the offspring. METHODS: We have designed a birth cohort of 250 families with prenatal recruitment (~ 14 weeks). We will genotype relevant allergy/asthma-associated variants in trios and will perform immunophenotyping and evaluation of allergy biomarkers in cord blood. At 1 and 2 years of age we will assess if infants have developed allergic sensitization, AD, FA, as well as biomarkers of asthma including the asthma predictive index. We will also evaluate how maternal conditions modify immune programming through epigenetic modifications and will then depict newborn epigenetic cues of allergy/asthma risk. Next, we will assess composition/diversity of maternal gut, placenta, breastmilk and infant gut microbiome and their association with immunophenotype and biomarkers at birth, and clinical outcomes at age 1 and 2. Finally, we plan to assess how environmental exposures (perinatal outdoor and indoor pollution, allergens and endotoxin) affect the incidence of allergic sensitization, AD, FA, and risk of asthma. DISCUSSION: The in-depth study of the ARIES birth cohort shall provide crucial information to understand the rising incidence of allergies and asthma in developing countries, and hopefully provide cues on how to prevent and treat these diseases. TRIAL REGISTRATION: clinicaltrials.gov NCT04186949, retrospectively registered on December 5, 2019.

A sumatriptan coarse-grained model to explore different environments: interplay with experimental techniques.

In this work, we developed a coarse-grained model of sumatriptan suitable for extensive molecular dynamics simulations. First, we confirmed the interfacial distribution of this drug in bilayers through cryogenic transmission electron microscopy and small-angle X-ray scattering techniques, as was predicted by our previous atomistic simulations. Based on these simulations, we developed a coarse-grained model for sumatriptan able to reproduce its overall molecular behavior, captured by atomistic simulations and experiments. We then tested the sumatriptan model in a micellar environment along with experimental characterization of sumatriptan-loaded micelles. The simulation results showed good agreement with photon correlation spectroscopy and electrophoretic mobility experiments performed in this work. The particle size of the obtained micelles was comparable with the simulated ones; meanwhile, zeta-potential results suggest adsorption of the drug on the micellar surface. This model is a step forward in the search for a suitable drug-delivery system for sumatriptan.

N-Acetylcysteine, a glutathione precursor, reverts vascular dysfunction and endothelial epigenetic programming in intrauterine growth restricted guinea pigs.

KEY POINTS: Intrauterine growth restriction (IUGR) is associated with vascular dysfunction, oxidative stress and signs of endothelial epigenetic programming of the umbilical vessels. There is no evidence that this epigenetic programming is occurring on systemic fetal arteries. In IUGR guinea pigs we studied the functional and epigenetic programming of endothelial nitric oxide synthase (eNOS) (Nos3 gene) in umbilical and systemic fetal arteries, addressing the role of oxidative stress in this process by maternal treatment with N-acetylcysteine (NAC) during the second half of gestation. The present study suggests that IUGR endothelial cells have common molecular markers of programming in umbilical and systemic arteries. Notably, maternal treatment with NAC restores fetal growth by increasing placental efficiency and reverting the functional and epigenetic programming of eNOS in arterial endothelium in IUGR guinea pigs. ABSTRACT: In humans, intrauterine growth restriction (IUGR) is associated with vascular dysfunction, oxidative stress and signs of endothelial programming in umbilical vessels. We aimed to determine the effects of maternal antioxidant treatment with N-acetylcysteine (NAC) on fetal endothelial function and endothelial nitric oxide synthase (eNOS) programming in IUGR guinea pigs. IUGR was induced by implanting ameroid constrictors on uterine arteries of pregnant guinea pigs at mid gestation, half of the sows receiving NAC in the drinking water (from day 34 until term). Fetal biometry and placental vascular resistance were followed by ultrasound throughout gestation. At term, umbilical arteries and fetal aortae were isolated to assess endothelial function by wire-myography. Primary cultures of endothelial cells (ECs) from fetal aorta, femoral and umbilical arteries were used to determine eNOS mRNA levels by quantitative PCR and analyse DNA methylation in the Nos3 promoter by pyrosequencing. Doppler ultrasound measurements showed that NAC reduced placental vascular resistance in IUGR (P < 0.05) and recovered fetal weight (P < 0.05), increasing fetal-to-placental ratio at term (∼40%) (P < 0.001). In IUGR, NAC treatment restored eNOS-dependent relaxation in aorta and umbilical arteries (P < 0.05), normalizing eNOS mRNA levels in EC fetal and umbilical arteries (P < 0.05). IUGR-derived ECs had a decreased DNA methylation (∼30%) at CpG -170 (from the transcription start site) and this epigenetic signature was absent in NAC-treated fetuses (P < 0.001). These data show that IUGR-ECs have common molecular markers of eNOS programming in umbilical and systemic arteries and this effect is prevented by maternal treatment with antioxidants.

Assessment of in vivo fetal growth and placental vascular function in a novel intrauterine growth restriction model of progressive uterine artery occlusion in guinea pigs.

Intra-uterine growth restriction (IUGR) is associated with short and long-term metabolic and cardiovascular alterations. Mice and rats have been extensively used to study the effects of IUGR, but there are notable differences in fetal and placental physiology relative to those of humans that argue for alternative animal models. This study proposes that gradual occlusion of uterine arteries from mid-gestation in pregnant guinea pigs produces a novel model to better assess human IUGR. Fetal biometry and in vivo placental vascular function were followed by sonography and Doppler of control pregnant guinea pigs and sows submitted to surgical placement of ameroid constrictors in both uterine arteries (IUGR) at mid-gestation (35 days). The ameroid constrictors induced a reduction in the fetal abdominal circumference growth rate (0.205 cm day(-1) ) compared to control (0.241 cm day(-1) , P < 0.001) without affecting biparietal diameter growth. Umbilical artery pulsatility and resistance indexes at 10 and 20 days after surgery were significantly higher in IUGR animals than controls (P < 0.01). These effects were associated with a decrease in the relative luminal area of placental chorionic arteries (21.3 ± 2.2% vs. 33.2 ± 2.7%, P < 0.01) in IUGR sows at near term. Uterine artery intervention reduced fetal (∼30%), placental (∼20%) and liver (∼50%) weights (P < 0.05), with an increased brain to liver ratio (P < 0.001) relative to the control group. These data demonstrate that the ameroid constrictor implantations in uterine arteries in pregnant guinea pigs lead to placental vascular dysfunction and altered fetal growth that induces asymmetric IUGR.

Insulin requires normal expression and signaling of insulin receptor A to reverse gestational diabetes-reduced adenosine transport in human umbilical vein endothelium.

Reduced adenosine uptake via human equilibrative nucleoside transporter 1 (hENT1) in human umbilical vein endothelial cells (HUVECs) from gestational diabetes mellitus (GDM) is reversed by insulin by restoring hENT1 expression. Insulin receptors A (IR-A) and B (IR-B) are expressed in HUVECs, and GDM results in higher IR-A mRNA expression vs. cells from normal pregnancies. We studied whether the reversal of GDM effects on transport by insulin depends on restoration of IR-A expression. We specifically measured hENT1 expression [mRNA, protein abundance, SLC29A1 (for hENT1) promoter activity] and activity (adenosine transport kinetics) and the role of IR-A/IR-B expression and signaling [total and phosphorylated 42 and 44 kDa mitogen-activated protein kinases (p44/42(mapk)) and Akt] in IR-A, IR-B, and IR-A/B knockdown HUVECs from normal (n = 33) or GDM (n = 33) pregnancies. GDM increases IR-A/IR-B mRNA expression (1.8-fold) and p44/42(mapk):Akt activity (2.7-fold) ratios. Insulin reversed GDM-reduced hENT1 expression and maximal transport capacity (V(max)/K(m)), and GDM-increased IR-A/IR-B mRNA expression and p44/42(mapk):Akt activity ratios to values in normal pregnancies. Insulin's effect was abolished in IR-A or IR-A/B knockdown cells. Thus, insulin requires normal IR-A expression and p44/42(mapk)/Akt signaling to restore GDM-reduced hENT1 expression and activity in HUVECs. This could be a protective mechanism for the placental macrovascular endothelial dysfunction seen in GDM.

Maternal hypercholesterolemia in pregnancy associates with umbilical vein endothelial dysfunction: role of endothelial nitric oxide synthase and arginase II.

OBJECTIVE: Human pregnancy that courses with maternal supraphysiological hypercholesterolemia (MSPH) correlates with atherosclerotic lesions in fetal arteries. It is known that hypercholesterolemia associates with endothelial dysfunction in adults, a phenomenon where nitric oxide (NO) and arginase are involved. However, nothing is reported on potential alterations in the fetoplacental endothelial function in MSPH. The aim of this study was to determine whether MSPH alters fetal vascular reactivity via endothelial arginase/urea and L-arginine transport/NO signaling pathways. APPROACH AND RESULTS: Total cholesterol <280 mg/dL was considered as maternal physiological hypercholesterolemia (n=46 women) and ≥ 280 mg/dL as MSPH (n=28 women). Maternal but not fetal total cholesterol and low-density lipoprotein-cholesterol levels were elevated in MSPH. Umbilical veins were used for vascular reactivity assays (wire myography), and primary cultures of umbilical vein endothelial cells to determine arginase, endothelial NO synthase (eNOS), and human cationic amino acid transporter 1 and human cationic amino acid transporter 2A/B expression and activity. MSPH reduced calcitonine gene-related peptide-umbilical vein relaxation and increased intima/media ratio (histochemistry), as well as reduced eNOS activity (L-citrulline synthesis from L-arginine, eNOS phosphorylation/dephosphorylation), but increased arginase activity and arginase II protein abundance. Arginase inhibition increased eNOS activity and L-arginine transport capacity without altering human cationic amino acid transporter 1 or human cationic amino acid transporter 2A/B protein abundance in maternal physiological hypercholesterolemia and MSPH. CONCLUSIONS: MSPH is a pathophysiological condition altering umbilical vein reactivity because of fetal endothelial dysfunction associated with arginase and eNOS signaling imbalance. We speculate that elevated maternal circulating cholesterol is a factor leading to fetal endothelial dysfunction, which could have serious consequences to the growing fetus.

Functional consequences of SARS-CoV-2 infection in pregnant women, fetoplacental unit, and neonate.

The SARS-CoV-2 infection causes COVID-19 disease, characterized by acute respiratory distress syndrome, bilateral pneumonia, and organ failure. The consequences of maternal SARS-CoV-2 infection for the pregnant woman, fetus, and neonate are controversial. Thus, it is required to determine whether there is viral and non-viral vertical transmission in COVID-19. The disease caused by SARS-CoV-2 leads to functional alterations in asymptomatic and symptomatic pregnant women, the fetoplacental unit and the neonate. Several diseases of pregnancy, including COVID-19, affect the fetoplacental function, which causes in utero programming for young and adult diseases. A generalized inflammatory state and a higher risk of infection are seen in pregnant women with COVID-19. Obesity, diabetes mellitus, and hypertension may increase the vulnerability of pregnant women to infection by SARS-CoV-2. Alpha, Delta, and Omicron variants of SARS-CoV-2 show specific mutations that seem to increase the capacity of the virus to infect the pregnant woman, likely due to increasing its interaction via the virus S protein and angiotensin-converting enzyme 2 receptors. This review shows the literature addressing to what extent COVID-19 in pregnancy affects the pregnant woman, fetoplacental unit, and neonate. Prospective studies that are key in managing SARS-CoV-2 infection in pregnancy are discussed.

Cellular mechanisms linking to outdoor and indoor air pollution damage during pregnancy.

Pregnancies are a critical window period for environmental influences over the mother and the offspring. There is a growing body of evidence associating indoor and outdoor air pollution exposure to adverse pregnancy outcomes such as preterm birth and hypertensive disorders of pregnancy. Particulate matter (PM) could trigger oxi-inflammation and could also reach the placenta leading to placental damage with fetal consequences. The combination of strategies such as risk assessment, advise about risks of environmental exposures to pregnant women, together with nutritional strategies and digital solutions to monitor air quality can be effective in mitigating the effects of air pollution during pregnancy.

TiO2-MWCNT nanohybrid: Cytotoxicity, protein corona formation and cellular internalisation in RTG-2 fish cell line.

Titanium dioxide nanoparticles-multiwalled carbon nanotubes (TiO2-MWCNT) nanohydrid has an enhanced photocatalytic activity across the visible light with promising applications in environmental remediation, solar energy devices and antimicrobial technologies. However, it is necessary to evaluate the toxicological effects of TiO2-MWCNT towards safe and sustainable development of nanohybrids. In this work, we studied the cytotoxicity, protein corona formation and cellular internalisation of TiO2-MWCNT on fibroblasts derived from gonadal rainbow trout tissue (RTG-2) for the first time. This nanohydrid did not show any toxicity effect on RTG-2 cells up to 100 mg L-1 after 24 h of exposure as monitored by alamar blue, neutral red and trypan blue assays (in presence or absence of foetal bovine serum, FBS). Futhermore, cryo-transmission electron microscopy analysis demonstrated that TiO2 particles is attached on nanotube surface after FBS-protein corona formation in cell culture medium. Raman spectroscopy imaging showed that TiO2-MWCNT can be internalised by RTG-2 cells. This work is a novel contribution towards better understanding the nanobiointeractions of nanohydrids linked to their in vitro effects on fish cells in aquatic nanoecotoxicology.

[Association of carotid intima media thickness with blood pressure and HDL cholesterol in children]. / La presión arterial es un importante marcador de ateroesclerosis subclínica en niños.

BACKGROUND: Cardiovascular risk factors must be controlled since childhood. AIM: To assess the association of carotid intima media thickness (CIMT) with the components of the metabolic syndrome in Children. MATERIAL AND METHODS: Cross sectional assessment of 299 children aged 11.5 ± 0.9 years (58% women) with and without metabolic syndrome components. Anthropometric parameters and blood pressure were measured and a blood sample was obtained to measure blood glucose and lipids. CIMT was measured using high resolution ultrasound. RESULTS: Ninety three percent of children were post puberal, 64% were overweight and 25% had metabolic syndrome. Mean and maximum CIMT correlated with systolic blood pressure (r = 0.21 and 0.21 respectively p < 0.01). Children with a CIMT over the 75th percentile had higher blood pressure and lower HDL cholesterol. A stepwise logistic regression accepted both variables as predictors of CIMT with odds ratios for mean CIMT of 1.46 (1.19-1-79) and 0.81 (0.7-0.94) per five units of change, respectively. CONCLUSIONS: In this group of children systolic blood pressure and HDL cholesterol are associated to CIMT.

PEGylated versus Non-PEGylated pH-Sensitive Liposomes: New Insights from a Comparative Antitumor Activity Study.

PEGylated liposomes are largely studied as long-circulating drug delivery systems. Nevertheless, the addition of PEG can result in reduced interactions between liposomes and cells, hindering liposomal internalization into target cells. The presence of PEG on the surface of pH-sensitive liposomes is not advantageous in terms of biodistribution and tumor uptake, raising the question of whether the indiscriminate use of PEG benefits the formulation. In this study, two doxorubicin-loaded pH-sensitive liposomal formulations, PEGylated (Lip2000-DOX) or non-PEGylated (Lip-DOX), were prepared and characterized. Overall, the PEGylated and non-PEGylated liposomes showed no differences in size or morphology in Cryo-TEM image analysis. Specifically, DLS analysis showed a mean diameter of 140 nm, PDI lower than 0.2, and zeta potential close to neutrality. Both formulations showed an EP higher than 90%. With respect to drug delivery, Lip-DOX had better cellular uptake than Lip2000-DOX, suggesting that the presence of PEG reduced the amount of intracellular DOX accumulation. The antitumor activities of free-DOX and both liposomal formulations were evaluated in 4T1 breast tumor-bearing BALB/c mice. The results showed that Lip-DOX was more effective in controlling tumor growth than other groups, inhibiting tumor growth by 60.4%. Histological lung analysis confirmed that none of the animals in the Lip-DOX group had metastatic foci. These results support that pH-sensitive liposomes have interesting antitumor properties and may produce important outcomes without PEG.

[Normal plasma insulin and HOMA values among Chilean children and adolescents]. / Insulinemia e índice HOMA en niños y adolescentes chilenos.

BACKGROUND: Plasma insulin and HOMA (homeostasis model assessment) index, used to determine insulin resistance, do not have local standard values for children and adolescents in Chile. AIM: To establish the normal reference intervals for insulin and HOMA in children and adolescents aged 10-15 years, according to sex and puberal maturation. MATERIAL AND METHODS: A cross-sectional study of 2,153 children and adolescents from Puente Alto County was performed, during 2009 and 2010. Anthropometry and self-report of puberal maturation were assessed. Fasting glucose (hexoquinase) and insulin blood levels (chemiluminiscence), were determined and HOMA index was calculated. Percentile distributions of these variables were calculated. RESULTS: The reference group included only subjects with normal body mass index and fasting blood glucose (n = 1,192). Girls had higher insulin and HOMA values than boys (12.5 ± 6.0 and 9.1 ± 4.9 µÏ‹/mL (p < 0.01) and 2.7 ± 1.4 and 2.1 ± 1,1 (p < 0.01), respectively). Subjects with Tanner I and II pubertal stages had lower insulin and HOMA mean values than subjects with Tanner III and IV (9.0 ± 4.3 and 12.5 ± 6.2µÏ‹/ml (p < 0.01) and2.0 ± 1 and2.8 ± 1.4 (p < 0.01), respectively). CONCLUSIONS: The 90th percentile of insulin and HOMA distributions according to sex and maturation, was selected as the upper cut-off point to identify individuals with insulin resistance. HOMA cutoff point for Tanner I and II boys was 3.2, for Tanner I and II girls was 4.1, for Tanner III and IV boys was 4.2 and for Tanner III and IV girls was 5.0.

[Combined influence of preconception body mass index and gestational weight gain on fetal growth]. / Influencia combinada del índice de masa corporal pregestacional y de la ganancia de peso en el embarazo sobre el crecimiento fetal.

BACKGROUND: The Chilean Ministry of Health has been using standards for nutritional evaluation and weight gain recommendations during pregnancy in the last 25 years. In the meantime new standards have been developed. AIM: To study the combined influence of preconception maternal nutritional status and gestational weight gain, using new standards to classify those parameters, on perinatal outcomes. MATERIAL AND METHODS: A cohort of 11,465 healthy pregnant women was prospectively followed until term. Their pre-gestational nutritional status was classified using the body mass index cut-offs in use in the United States (USA). Their gestational weight gain was classified using categories proposed in a Danish study. Perinatal outcomes included were risky birth weight, i.e. < 3000 g and ≥ 4000 g, and cesarean delivery. Relative risks for those perinatal outcomes were calculated for all combined categories of pre-gestational nutritional status and gestational weight gain. RESULTS: Relative risks of almost all gestational weight gain results were statistically significant for women having a normal pre-gestational nutritional status meanwhile all of them were not significant for underweight women. Overweight and obese women had similar relative risks values as normal women. However, many of them were not significant, especially in obese women. CONCLUSIONS: There is an independent and combined influence of preconception nutritional status and gestational weight gain on perinatal outcomes, when using standards to classify those parameters developed in the USA and Denmark, respectively.

Comparison of Three Gestational Weight Gain Guidelines Under Use in Latin America.

Presently, three guidelines are used in Latin America to assess adequacy of maternal body mass index (BMI) during pregnancy: (1) the chart proposed by the Institute of Medicine of the United States (IOM), (2) the Rosso-Mardones Chart (RM), and (3) a modified RM chart proposed by Atalah et al. (AEA). The aim of the present review was to explore available information on the sensitivity, specificity, and both positive (PPV) and negative predictive values (NPV) of these charts to detect women at risk of delivering babies with the following signs of abnormal fetal growth: (a) length at birth (BL) <50 cm; (b) birth weight (BW) <3,000 g; and (c) BW ≥ 4,000 or 4,250 g. Data from studies conducted in large samples of Chilean and Uruguayan women indicate that the RM chart has the greatest sensitivity to identify at risk cases. However, predictive values were similar for the three charts. Thus, the use of the RM chart should be preferred. The main limitation for using the IOM weight gain recommendations in Latin American women stems from the fact that their average height is approximately 20 cm lower than US women.

An atomic model for the human septin hexamer by cryo-EM.

In order to form functional filaments, human septins must assemble into hetero-oligomeric rod-like particles which polymerize end-to-end. The rules governing the assembly of these particles and the subsequent filaments are incompletely understood. Although crystallographic approaches have been successful in studying the separate components of the system, there has been difficulty in obtaining high resolution structures of the full particle. Here we report a first cryo-EM structure for a hexameric rod composed of human septins 2, 6 and 7 with a global resolution of ~3.6 Å and a local resolution of between ~3.0 Å and ~5.0 Å. By fitting the previously determined high-resolution crystal structures of the component subunits into the cryo-EM map, we are able to provide an essentially complete model for the particle. This exposes SEPT2 NC-interfaces at the termini of the hexamer and leaves internal cavities between the SEPT6-SEPT7 pairs. The floor of the cavity is formed by the two α0 helices including their polybasic regions. These are locked into place between the two subunits by interactions made with the α5 and α6 helices of the neighbouring monomer together with its polyacidic region. The cavity may serve to provide space allowing the subunits to move with respect to one another. The elongated particle shows a tendency to bend at its centre where two copies of SEPT7 form a homodimeric G-interface. Such bending is almost certainly related to the ability of septin filaments to recognize and even induce membrane curvature.

Visualization of supramolecular structure of Pluronic F127 micellar hydrogels using cryo-TEM.

Pluronic® F127 micellar hydrogels are of growing interest to the biomedical field due to their versatility as drug delivery systems. Pluronic® F127 is a symmetric and amphiphilic triblock copolymer which in aqueous medium self-assembles into micelles that pack togetherwith increasing temperature or concentration, leading to non-flowable hydrogels. The microstructure of these hydrogels is usually investigated by small-angle X-ray scattering, which is not a readily available technique. Conversely, cryo-TEM is a widespread technique used for investigating the morphology of aqueous systems. In the case of Pluronic® F127 micellar systems, the elevated viscosity poses a significant challenge for specimen preparation and, consequently, for cryo-TEM observation. Herein, we show a trustworthy, inexpensive and readily available methodology for preparing specimens of highly viscous micellar solutions and non-flowable hydrogels using an automated vitrification system. With this methodology we were able to visualize not only the morphology of individual Pluronic® F127 micelles -but also the supramolecular structure evolution as a function of concentration. This methodology opens up a wide range of opportunities for hydrogel characterization, although additional systematic studies might be required in order to optimize and replicate it for similar systems.