Postnatal growth failure of very low-birth-weight infants in Southwest Iran: A descriptive analytical study

Background and Aims

Preterm infants are more prone to poor growth and neurodevelopment. The first few weeks of life play an important role in the growth and neurodevelopment of very-low-birth-weight (VLBW) infants. The Vermont Oxford Network, evaluating the postnatal growth of preterm newborns, considers growth failure as body weight <10th percentile for postmenstrual age. This study aims to assess the frequency of postnatal growth failure in VLBW infants in Southwest Iran.

Methods

This descriptive analytical study was performed on VLBW infants in the neonatal intensive care unit (NICU) of Imam Khomeini Hospital (Ahvaz, Iran) from September 2019 to August 2020. Growth failure was confirmed when a newborn's weight at discharge was smaller than the 10th percentile corrected age (≤-1.28 Z-score), based on the Fenton growth chart as a standard. This study was performed on 353 infants. Intrauterine growth retardation was detected in 29% of female and 10.6% of male newborns, who were born at a gestational age of 32 and 31 weeks or higher respectively. Upon hospital discharge, postnatal growth failure was detected in all newborn girls, except for those born at 32 weeks of gestation, and all newborn boys, except for those born at a gestational age of 33-34 weeks.

Conclusion

Postnatal growth retardation in VLBW infants born in our NICU was much higher than that of other centers. Overcrowding, short length of hospitalization, low nurse-to-patient ratio, and untrained nurses were among the reasons for poor postnatal growth in our center.

Ultra-high-density 3D DNA arrays within nanoporous biocompatible membranes for single-molecule-level detection and purification of circulating nucleic acids

Extracellular nucleic acids freely circulating in blood and other physiologic fluids are important biomarkers for non-invasive diagnostics and early detection of cancer and other diseases, yet difficult to detect because they exist in very low concentrations and large volumes. Here we demonstrate a new broad-range sensor platform for ultrasensitive and selective detection of circulating DNA down to the single-molecule level. The biosensor is based on a chemically functionalized nanoporous diamond-like carbon (DLC) coated alumina membrane. The few nanometer-thick, yet perfect and continuous DLC-coating confers the chemical stability and biocompatibility of the sensor, allowing its direct application in biological conditions. The selective detection is based on complementary hybridization of a fluorescently-tagged circulating cancer oncomarker (a 21-mer nucleic acid) with covalently immobilized DNA on the surface of the membrane. The captured DNAs are detected in the nanoporous structure of the sensor using confocal scanning laser microscopy. The flow-through membrane sensor demonstrates broad-range sensitivity, spanning from 10(15) molecules per cm(2) down to single molecules, which is several orders of magnitude improvement compared to the flat DNA microarrays. Our study suggests that these flow-through type nanoporous sensors represent a new powerful platform for large volume sampling and ultrasensitive detection of different chemical biomarkers.

Surface charge effects in protein adsorption on nanodiamonds

Understanding the interaction of proteins with charged diamond nanoparticles is of fundamental importance for diverse biomedical applications. Here we present a thorough study of protein binding, adsorption kinetics and structure on strongly positively (hydrogen-terminated) and negatively (oxygen-terminated) charged nanodiamond particles using a quartz crystal microbalance by dissipation and infrared spectroscopy. By using two model proteins (bovine serum albumin and lysozyme) of different properties (charge, molecular weight and rigidity), the main driving mechanism responsible for the protein binding to the charged nanoparticles was identified. Electrostatic interactions were found to dominate the protein adsorption dynamics, attachment and conformation. We developed a simple electrostatic model that can qualitatively explain the observed adsorption behaviour based on charge-induced pH modifications near the charged nanoparticle surfaces. Under neutral conditions, the local pH around the positively and negatively charged nanodiamonds becomes very high (11-12) and low (1-3) respectively, which has a profound impact on the protein charge, hydration and affinity to the nanodiamonds. Small proteins (lysozyme) were found to form multilayers with significant conformational changes to screen the surface charge, while larger proteins (albumin) formed monolayers with minor conformational changes. The findings of this study provide a step forward toward understanding and eventually predicting nanoparticle interactions with biofluids.