Factors associated with high exclusive breastfeeding rates among preterm infants under 34 weeks of gestation in Da Nang, Vietnam: A retrospective cohort study

Background

Preterm infants have higher mortality than full-term infants. While breastfeeding dramatically reduces preterm death, it is limited by biological and practice barriers, particularly for babies born before 34 weeks gestational age. Da Nang Hospital for Women and Children developed a quality improvement approach to improve breastfeeding of preterm infants by strengthening feeding support, non-separation, and kangaroo mother care (KMC).

Methods

To determine breastfeeding outcomes following discharge and explore factors associated with improved feeding, mothers of infants under 34 weeks gestational age born October 2021 to March 2022 and discharged alive were interviewed at six months and their medical records were reviewed.

Results

Out of 104 preterm infants included, all were exclusively breastfed at discharge and one month, 86.5% at three months, and 63.5% at six months; 47.1% received immediate skin-to-skin contact, 31.7% immediate and continuous KMC, and the remaining 68.3% continuous KMC beginning at a median of three days. Exclusive breastfeeding at six months was associated with the mother antenatally seeking breastfeeding information (odds ratio (OR) = 14.5; 95% confidence interval (CI) = 1.2-173.6), avoiding bottle-feeding at home (OR = 7.7; 95% CI = 1.7-33.7) and reduced with each day delay between birth and full breastfeeding (OR = 0.8; 95% CI = 0.6-0.9).

Conclusions

Hospital environments that limit mother-baby separations and feeding delays, including rooming-in of mothers and infants, KMC, and breastfeeding support from birth, enabled 100% of preterm infants born before 34 weeks gestational age to breastfeed exclusively with continued rates higher than previously reported. Addressing antenatal and post-natal factors limiting practice can further improve longer-term breastfeeding outcomes. The approach can be adapted to achieve high exclusive breastfeeding rates, regardless of gestational age.

Bioavailability of octamethylcyclotetrasiloxane (D(4)) after exposure to silicones by inhalation and implantation

We developed a physiologically based pharmacokinetic (PBPK) model to predict the target organ doses of octamethylcyclotetrasiloxane (D(4)) after intravenous (IV), inhalation, or implantation exposures. The model used (14)C-D(4) IV disposition data in rats to estimate tissue distribution coefficients, metabolism, and excretion parameters. We validated the model by comparing the predicted blood and tissues concentrations of D(4) after inhalation to experimental results in both rats and humans. We then used the model to simulate D(4) kinetics after single and/or repeated D(4) exposures in rats and humans. The model predicted bioaccumulation of D(4) in fatty tissues (e.g., breast), especially in women. Because of its high lipid solubility (Log P(oct/water) = 5.1), D(4) persisted in fat with a half life of 11.1 days after inhalation and 18.2 days after breast implant exposure. Metabolism and excretion remained constant with repeated exposures, larger doses, and/or different routes of exposure. The accumulation of D(4) in fatty tissues should play an important role in the risk assessment of D(4) especially in women exposed daily to multiple personal care products and silicone breast implants.

Prediction of the shelf life of cellulose acetate hemodialyzers by Monte Carlo simulation

A previous investigation by our laboratory linked cellulose acetate degradation with adverse health effects in hemodialysis patients. To establish the accumulation of degradation products with time, a Monte Carlo model of degradation kinetics was developed. The model tracks changes in a population of molecules representative of the dialyzer membrane during the degradation process. The degradation calculation is a two step process: First, the model uses a random number to select an individual polymer molecule out of the population, and then a second random number is used to identify a site on the selected molecule for the degradation reaction to occur. After the reaction calculation, the resulting degraded molecules are redistributed into the population. The course of the reaction is determined by recalculating the molecular weight averages in the changing population as the calculations proceed. The model was validated using gel permeation chromatography molecular weight results and total acetyl content measurements on dialyzers stored up to 13.3 years after manufacture. It was found that the degradation reactions can be accurately modeled as random events and that the chain scissions and deacetylation events occur at constant rates. The shelf life of these devices was estimated using the model predictions and animal test results.

Physiologically based pharmacokinetic model for fluorocarbon elimination after the administration of an octafluoropropane-albumin microsphere sonographic contrast agent

A physiologically based pharmacokinetic model was developed to evaluate the kinetics of one of the newest sonographic contrast agents available, FS069 or Optison. This material consists of octafluoropropane gas encapsulated in proteinaceous microspheres, injected intravenously for use as a myocardial contrast agent in humans. This model has six compartments: two lung compartments (alveolar and dead volume), and compartments for the heart, slowly perfused tissue, richly perfused tissue, and gastrointestinal tract. The model was developed to determine the distribution and excretion of the octafluoropropane in the body. Despite the high affinity of octafluoropropane for tissue, the model predicted that nearly 100% of the material would be exhaled from the lungs within 6 min. The model verified the results of a phase I clinical trial with 10 healthy subjects. Ventilation rate was found to play a critical role in the complete excretion of this contrast agent. The physiologically based pharmacokinetic model was a useful tool for evaluating the safety of FS069. This model can be used a basis for developing similar models for other types of contrast agents.

A physiologically based pharmacokinetic model for 2,4-toluenediamine leached from polyurethane foam-covered breast implants

Physiologically based pharmacokinetic (PBPK) modeling was used to assess the low-dose exposure of patients to the carcinogen 2, 4-toluenediamine (2,4-TDA) released from the degradation of the polyester urethane foam (PU) used in Meme silicone breast implants. The tissues are represented as five compartments: liver, kidney, gastrointestinal tract, slowly perfused tissues (e.g., fat), and richly perfused tissues (e.g., muscle). The PBPK model was fitted to the plasma and urine concentrations of 2,4-TDA and its metabolite 4-AAT (4-N-acetyl-2-amino toluene) in rats given low doses of 2, 4-TDA intravenously and subcutaneously. The rat model was extrapolated to simulate oral and implant routes in rats. After adjusting for human physiological parameters, the model was then used to predict the bioavailability of 2,4-TDA released from a typical 4.87-g polyester urethane foam implant found in a patient who weighed 58 kg with the Meme and had the breast implant for 10 years. A quantitative risk assessment for 2,4-TDA was performed and the polyester urethane foam did present an unreasonable risk to health for the patient.

Characterization of [3H]ouabain binding sites in human brain, platelet, and erythrocyte

[3H]Ouabain binding was investigated in membranes prepared from human brain, erythrocyte, and platelet. Scatchard analysis of [3H]ouabain binding to human hypothalamic membranes revealed a single class of noninteracting binding sites with an apparent affinity constant (KD) of 21 nM. Though the number of [3H]ouabain binding sites was lower in human platelets than in erythrocytes, both tissues exhibited a single class of high-affinity binding sites with an apparent KD similar to that found in human brain. Specific [3H]ouabain binding in basal ganglia tissue from patients with Huntington's disease was more than 50% lower than in tissue from age- and sex-matched controls. These results, along with previous findings in rat brain, suggest that high-affinity [3H]ouabain binding labels the neuronal form of Na, K-ATPase in human brain, and may prove useful in quantitating this enzyme in postmortem brain samples.

Characterization of "high-affinity" [3H]ouabain binding in the rat central nervous system

The characteristics of [3H]ouabain binding were examined in various areas of rat brain. In the striatum, Scatchard analysis revealed a single class of "high-affinity" binding sites with an apparent binding affinity (KD) of 10.4 +/- 0.9 nM and an estimated binding capacity (Bmax) of 7.6 +/- 1.9 pmol/mg protein. Similar monophasic Scatchard plots were found in the brainstem, cerebellum, hypothalamus, and frontal cerebral cortex. [3H]Ouabain binding to rat brain was sodium- and ATP-dependent and strongly inhibited by potassium. Proscillariden A was the most potent cardiac glycoside tested in inhibiting specific [3H]ouabain binding to brain membranes, and the rank order of inhibitory potencies for a series of cardiac glycosides was similar to that previously reported for inhibition of heart Na,K-ATPase. To assess whether the high-affinity binding sites for [3H]ouabain were localized to neuronal or nonneuronal membranes, the effect of discrete kainic acid lesions on striatal [3H]ouabain binding was examined. Kainic acid lesions of the striatum reduced [3H]ouabain binding to striatal homogenates by 79.6 +/- 1.6%. This suggests that the "high-affinity" [3H]ouabain binding sites measured in our experiments are localized to neuronal elements. Thus, the high-affinity binding of [3H]ouabain to brain membranes may selectively label a neuronal form or conformation of Na,K-ATPase.