Vasopressin in newborns with refractory acute pulmonary hypertension

BACKGROUND

Acute pulmonary hypertension (aPH) in newborns can be life threatening and challenging to manage. In newborns with refractory aPH, there is currently limited therapeutic agents.

METHODS

Retrospective single-center cohort study in newborns less than one month old who were treated with vasopressin for a minimum of one hour in the context of refractory aPH in the neonatal and pediatric intensive care units of a tertiary university center between 2016 and 2022. The objective was to evaluate the efficacy and safety of vasopressin in newborns as an adjuvant treatment for refractory aPH.

RESULTS

Twenty-five patients met inclusion criteria. In patients who received vasopressin, oxygenation index improved from 28.4 to 14.4 (p = 0.004) after twelve hours of continuous infusion. Oxygen requirements (FiO2) decreased from 0.91 to 0.50 (p = 0.004) and mean arterial pressure increased from 41 to 51 mmHg (p = 0.001). In our cohort, 68% of patients presented an episode of hyponatremia (serum sodium <130 mmol/L).

CONCLUSIONS

The use of vasopressin may be associated with improvement in oxygenation and hemodynamic status of neonatal patients with aPH refractory to initial therapy. Further prospective studies are needed to establish the safety profile of vasopressin in newborns, particularly in preterm infants.

IMPACT

Vasopressin may be an effective cardiotropic agent to improve oxygenation and hemodynamic status in newborns with acute pulmonary hypertension. Careful monitoring of serum sodium levels are warranted in newborns who are receiving vasopressin infusion. This provides additional evidence for the consideration of vasopressin in newborns with acute pulmonary hypertension refractory to inhaled nitric oxide.

CPAP Versus NIPPV Postextubation in Preterm Neonates: A Comparative-Effectiveness Study

BACKGROUND AND OBJECTIVES

Nasal intermittent positive pressure ventilation (NIPPV) has been shown to be superior to nasal continuous positive airway pressure (CPAP) postextubation in preterm neonates. However, studies have not permitted high CPAP pressures or rescue with other modes. We hypothesized that if CPAP pressures >8 cmH2O and rescue with other modes were permitted, CPAP would be noninferior to NIPPV.

METHODS

We conducted a pragmatic, comparative-effectiveness, noninferiority study utilizing network-based real-world data from 22 Canadian NICUs. Centers self-selected CPAP or NIPPV as their standard postextubation mode for preterm neonates <29 weeks' gestation. The primary outcome was failure of the initial mode ≤72 hours. Secondary outcomes included failure ≤7 days, and reintubation ≤72 hours and ≤7 days. Groups were compared using a noninferiority adjusted risk-difference (aRD) margin of 0.05, and margin of no difference.

RESULTS

A total of 843 infants extubated to CPAP and 974 extubated to NIPPV were included. CPAP was not noninferior (and inferior) to NIPPV for failure of the initial mode ≤72 hours (33.0% vs 26.3%; aRD 0.07 [0.03 to 0.12], Pnoninferiority(NI) = .86), and ≤7 days (40.7% vs 35.8%; aRD 0.09 [0.05 to 0.13], PNI = 0.97). However, CPAP was noninferior (and equivalent) to NIPPV for reintubation ≤72 hours (13.2% vs 16.1%; aRD 0.01 [-0.05 to 0.02], PNI < .01), and noninferior (and superior) for reintubation ≤7 days (16.4% vs 22.8%; aRD -0.04 [-0.07 to -0.001], PNI < .01).

CONCLUSIONS

CPAP was not noninferior to NIPPV for failure ≤72 hours postextubation; however, it was noninferior to NIPPV for reintubation ≤72 hours and ≤7 days. This suggests CPAP may be a reasonable initial postextubation mode if alternate rescue strategies are available.

Association of Weight Changes by Three Days after Birth and Mortality and/or Severe Neurological Injury in Preterm Infants < 29 Weeks Gestational Age: A Multicenter Cohort Study

Objective: This study aimed to determine the range of weight loss, at 3 days postnatal age, associated with the lowest risk of mortality/short-term morbidity in preterm infants <29 weeks gestational age (GA). Study design: This multicenter retrospective cohort study employed data from the Canadian Neonatal Network database. The primary outcome was a composite of mortality and/or severe neurological injury. Multivariable quadratic and linear regression models which adjusted for potential confounders were built. Results: A total of 9275 preterm infants (median GA 26, IQR 25, 28 weeks) were included. The optimal weight change range at day three, after adjustment for potential confounders for the primary outcomes, was −15 to −8.9%. Conclusions: There is a ‘U’-shaped relationship between weight change from birth to day three and mortality and/or severe neurological injury. Interventional studies, which target weight loss within the range found in this study and evaluate the impact on neonatal outcomes, are needed to corroborate our findings.

31 Noninvasive high-frequency oscillatory ventilation in preterm infants: Safe and effective

Primary Subject area

Neonatal-Perinatal Medicine

Background

Mechanical ventilation is frequently used in preterm infants for various indications, but is associated with multiple complications, including bronchopulmonary dysplasia and poorer neurodevelopmental outcomes. Noninvasive high-frequency oscillatory ventilation (nHFOV) is a noninvasive ventilation (NIV) strategy used to avoid mechanical ventilation and associated complications. However, its effectiveness remains controversial, and its safety has not been established.

Objectives

The objectives were to evaluate the effectiveness of nHFOV to prevent intubations and support adequate ventilation in preterm infants, and to assess its safety profile.

Design/Methods

This was a retrospective crossover case study including 24 infants and 30 nHFOV instances between May 2018 and June 2020. Infants were included if they were placed on nHFOV for at least one hour; each nHFOV trial contributed as one instance. Data was collected from health records. Effectiveness outcomes were: successful transition to another NIV mode without requiring intubation, and variations in CO2, FiO2, and number of spells. Safety outcomes were: apparition of intraventricular hemorrhage (IVH), gastrointestinal complications, nasal cutaneous trauma, and comfort as assessed with the Neonatal Pain, Agitation and Sedation Scale (N-PASS). Descriptive statistics were used for baseline characteristics. Nonparametric and semiparametric tests were used to compare outcomes pre- and during nHFOV.

Results

Baseline characteristics are presented in Table 1. At initiation of nHFOV, mean chronological age and weight were 24 days (95% CI: 20 – 28) and 1119 grams (95% CI: 1038 – 1200) respectively. The most frequent indication for nHFOV was spells (56.7%), and the mean duration of nHFOV instances was 3.9 days (95% CI: 2.7 – 5.1) (Table 1). In 18 (60%) cases, infants transitioned successfully to another NIV mode without requiring intubation. Levels of CO2 and number of spells were significantly lower during nHFOV than pre-nHFOV. There was no significant difference in FiO2 pre-nHFOV and during nHFOV. No apparition or progression of IVH was observed following the use of nHFOV. There was no significant difference in N-PASS, nasal trauma, and gastrointestinal complications pre-nHFOV and during nHFOV (Table 2).

Conclusion

This study suggests that nHFOV is an effective ventilation method to avoid intubation and to decrease spells in preterm infants, without increasing complications.

Neurodevelopmental outcomes of preterm infants conceived by assisted reproductive technology

BACKGROUND

There have been concerns about the development of children conceived through assisted reproductive technology. Despite multiple studies investigating the outcomes of assisted conception, data focusing specifically on the neurodevelopmental outcomes of infants conceived through assisted reproductive technology and born preterm are limited.

OBJECTIVE

This study aimed to evaluate and compare the neurodevelopmental outcomes of preterm infants born at <29 weeks' gestation at 18 to 24 months' corrected age who were conceived through assisted reproductive technology and those who were conceived naturally.

STUDY DESIGN

This retrospective cohort study included inborn, nonanomalous infants, born at <29 weeks' gestation between January 1, 2010, and December 31, 2016, who had a neurodevelopmental assessment at 18 to 24 months' corrected age at any of the 10 Canadian Neonatal Follow-Up Network clinics. The primary outcome was neurodevelopmental impairment at 18 to 24 months, defined as the presence of any of the following: cerebral palsy; Bayley-III cognitive, motor, or language composite score of <85; sensorineural or mixed hearing loss; and unilateral or bilateral visual impairment. Secondary outcomes included mortality, composite of mortality or neurodevelopmental impairment, significant neurodevelopmental impairment, and each component of the primary outcome. We compared outcomes between infants conceived through assisted reproductive technology and those conceived naturally, using bivariate and multivariable analyses after adjustment.

RESULTS

Of the 4863 eligible neonates, 651 (13.4%) were conceived using assisted reproductive technology. Maternal age; education level; and rates of diabetes mellitus, receipt of antenatal corticosteroids, and cesarean delivery were higher in the assisted reproduction group than the natural conception group. Neonatal morbidity and death rates were similar except for intraventricular hemorrhage, which was lower in the assisted reproduction group (33% [181 of 546] vs 39% [1284 of 3318]; P=.01). Of the 4176 surviving infants, 3386 (81%) had a follow-up outcome at 18 to 24 months' corrected age. Multivariable logistic regression adjusting for gestational age, antenatal steroids, sex, small for gestational age, multiple gestations, mode of delivery, maternal age, maternal education, pregnancy-induced hypertension, maternal diabetes mellitus, and smoking showed that infants conceived through assisted reproduction was associated with lower odds of neurodevelopmental impairment (adjusted odds ratio, 0.67; 95% confidence interval, 0.52-0.86) and the composite of death or neurodevelopmental impairment (adjusted odds ratio, 0.67; 95% confidence interval, 0.54-0.84). Conception through assisted reproductive technology was associated with decreased odds of a Bayley-III composite cognitive score of <85 (adjusted odds ratio, 0.68; 95% confidence interval, 0.48-0.99) and composite language score of <85 (adjusted odds ratio, 0.67; 95% confidence interval, 0.50-0.88).

CONCLUSION

Compared with natural conception, assisted conception was associated with lower odds of adverse neurodevelopmental outcomes, especially cognitive and language outcomes, at 18 to 24 months' corrected age among preterm infants born at <29 weeks' gestation. Long-term follow-up studies are required to assess the risks of learning disabilities and development of complex visual-spatial and processing skills in these children as they reach school age.

Study of the effect of anaesthesia on the canine ultrasonographic optic nerve sheath diameter

OBJECTIVES

To investigate the effects of anaesthetic duration and serial anaesthetic events on optic nerve sheath diameter in a population of dogs without intracranial disease using point-of-care ultrasonography.

MATERIALS AND METHODS

Client-owned dogs requiring advanced head imaging were prospectively enrolled. Exclusion criteria included signs of elevated intracranial pressure, glaucoma and optic nerve disease. Using a transpalpebral technique, two optic nerve sheath diameter measurements were recorded for each eye at three timepoints: following premedication, after induction within 7 minutes and before discontinuing isoflurane. Mixed model analysis was used to characterise optic nerve sheath diameter behaviour and investigate the effects of anaesthetic duration, bodyweight and anaesthetic protocol, age and sex.

RESULTS

Fourteen dogs of various ages, breeds and bodyweights were enrolled. A positive linear relationship was detected between body weight and optic nerve sheath diameter. In 12 of 14 dogs, the optic nerve sheath diameter increased from measurements taken after premedication when compared to measurements taken after induction within 7 minutes. In a subset of patients, measurements subsequently decreased when anaesthetic duration exceeded 120 minutes. Age, side, sex, final body temperature, blood pressure and anaesthetic protocol did not significantly affect optic nerve sheath diameter. No significant association was noted between optic nerve sheath diameter and end-tidal carbon dioxide after induction and before discontinuing isoflurane.

CLINICAL SIGNIFICANCE

When using point-of-care ultrasound, a transient increase in optic nerve sheath diameter occurs between premedication and within 7 minutes following induction, regardless of bodyweight. This should be taken into consideration when serial monitoring is performed.

Neurodevelopmental outcomes of singleton large for gestational age infants <29 weeks' gestation: a retrospective cohort study

OBJECTIVE

To compare neurodevelopmental outcomes of large and appropriate for gestational age (LGA, AGA) infants <29 weeks' gestation at 18-24 months of corrected age.

STUDY DESIGN

Retrospective cohort study using the Canadian Neonatal Network and Canadian Neonatal Follow-Up Network databases. Primary outcome was a composite of death or significant neurodevelopmental impairment (NDI), defined as severe cerebral palsy, Bayley III cognitive, language and motor scores of <70, need for hearing aids or cochlear implant and bilateral visual impairment. Univariate and multivariable logistic analyses were applied for outcomes.

RESULTS

The study cohort comprised 170 LGA and 1738 AGA infants. There was no difference in significant NDI or individual components of the Bayley III between LGA and AGA groups. LGA was associated with the increased risk of death by follow-up, 44/170 (25.9%) vs. 320/1738 (18.4%) (aOR: 1.60 95% CI: 1.00-2.54).

CONCLUSIONS

Risk of NDI was similar between LGA and AGA infants.

Relative effectiveness and safety of pharmacotherapeutic agents for patent ductus arteriosus (PDA) in preterm infants: a protocol for a multicentre comparative effectiveness study (CANRxPDA)

INTRODUCTION

Patent ductus arteriosus (PDA) is the most common cardiovascular problem that develops in preterm infants and evidence regarding the best treatment approach is lacking. Currently available medical options to treat a PDA include indomethacin, ibuprofen or acetaminophen. Wide variation exists in PDA treatment practices across Canada. In view of this large practice variation across Canadian neonatal intensive care units (NICUs), we plan to conduct a comparative effectiveness study of the different pharmacotherapeutic agents used to treat the PDA in preterm infants.

METHODS AND ANALYSIS

A multicentre prospective observational comparative-effectiveness research study of extremely preterm infants born <29 weeks gestational age with an echocardiography confirmed PDA will be conducted. All participating sites will self-select and adhere to one of the following primary pharmacotherapy protocols for all preterm babies who are deemed to require treatment.Standard dose ibuprofen (10 mg/kg followed by two doses of 5 mg/kg at 24 hours intervals) irrespective of postnatal age (oral/intravenous).Adjustable dose ibuprofen (oral/intravenous) (10 mg/kg followed by two doses of 5 mg/kg at 24 hours intervals if treated within the first 7 days after birth. Higher doses of ibuprofen up to 20 mg/kg followed by two doses of 10 mg/kg at 24 hours intervals if treated after the postnatal age cut-off for lower dose as per the local centre policy).Acetaminophen (oral/intravenous) (15 mg/kg every 6 hours) for 3-7 days.Intravenous indomethacin (0.1-0.3 mg/kg intravenous every 12-24 hours for a total of three doses).

OUTCOMES

The primary outcome is failure of primary pharmacotherapy (defined as need for further medical and/or surgical/interventional treatment following an initial course of pharmacotherapy). The secondary outcomes include components of the primary outcome as well as clinical outcomes related to response to treatment or adverse effects of treatment.

SITES AND SAMPLE SIZE

The study will be conducted in 22 NICUs across Canada with an anticipated enrollment of 1350 extremely preterm infants over 3 years.

ANALYSIS

To examine the relative effectiveness of the four treatment strategies, the primary outcome will be compared pairwise between the treatment groups using χ² test. Secondary outcomes will be compared pairwise between the treatment groups using χ² test, Student's t-test or Wilcoxon rank sum test as appropriate. To further examine differences in the primary and secondary outcomes between the four groups, multiple logistic or linear regression models will be applied for each outcome on the treatment groups, adjusted for potential confounders using generalised estimating equations to account for within-unit-clustering. As a sensitivity analysis, the difference in the primary and secondary outcomes between the treatment groups will also be examined using propensity score method with inverse probability weighting approach.

ETHICS AND DISSEMINATION

The study has been approved by the IWK Research Ethics Board (#1025627) as well as the respective institutional review boards of the participating centres.

TRIAL REGISTRATION NUMBER

NCT04347720.

The Use of Restraint and Seclusion in Residential Treatment Care for Youth: A Systematic Review of Related Factors and Interventions

Children placed in residential treatment centers (RTCs) typically present challenging behavior including aggression. In this context, restraint and seclusion (R&S) are seen as "last resort" strategies for educators to manage youth aggression. The use of R&S is controversial, as they can lead to psychological and physical consequences for both the client and the care provider and have yet to be empirically validated as therapeutic. The objectives of this systematic review are to identify the factors related to R&S use in RTCs for youth and to review the interventions aiming to reduce the use of R&S. The identification of these factors is the first step to gaining a better understanding of the decision-making process leading to the use of R&S and ultimately to reducing the use of these strategies to a minimum. Thus, the present systematic review was conducted by searching PubMed, CINAHL, ERIC, and PsycNET for articles published between 2002 and 2017. Key words used were synonyms of R&S, youth, and RTCs. Thirty-one studies met the inclusion criteria: must report on factors affecting the use of R&S in RTCs, must be conducted in RTCs for youth under the age of 21, and must report on original and empirical data. Factors related to the characteristics of the client, the care provider, and the environment, as well as to the implementation of programs for the reduction of R&S, were found to influence the use of R&S in RTCs. A conceptual model is presented. The implementation of programs to reduce R&S use is discussed.

Severe Neurodevelopmental Impairment in Neonates Born Preterm: Impact of Varying Definitions in a Canadian Cohort

OBJECTIVE

To assess the impact of variations in the definition of severe neurodevelopmental impairment (NDI) on the incidence of severe NDI and the association with risk factors using the Canadian Neonatal Follow-Up Network cohort.

STUDY DESIGN

Literature review of severe NDI definitions and application of these definitions were performed in this database cohort study. Infants born at 23-28 completed weeks of gestation between 2009 and 2011 (n = 2187) admitted to a Canadian Neonatal Network neonatal intensive care unit and assessed at 21 months' corrected age were included. The incidence of severe NDI, aORs, and 95% CIs were calculated to express the relationship between risk factors and severe NDI using the definitions with the highest and the lowest incidence rates of severe NDI.

RESULTS

The incidence of severe NDI ranged from 3.5% to 14.9% (highest vs lowest rate ratio 4.29; 95% CI 3.37-5.47). The associations between risk factors and severe NDI varied depending on the definition used. Maternal ethnicity, employment status, antenatal corticosteroid treatment, and gestational age were not associated consistently with severe NDI. Although maternal substance use, sex, score of neonatal acute physiology >20, late-onset sepsis, bronchopulmonary dysplasia, and brain injury were consistently associated with severe NDI irrespective of definition, the strength of the associations varied.

CONCLUSIONS

The definition of severe NDI significantly influences the incidence and the associations between risk factors and severe NDI. A standardized definition would facilitate site comparisons and scientific communication.

Neurodevelopmental Outcomes of Infants Born at <29 Weeks of Gestation Admitted to Canadian Neonatal Intensive Care Units Based on Location of Birth

OBJECTIVE

To compare mortality and neurodevelopmental outcomes of outborn and inborn preterm infants born at <29 weeks of gestation admitted to Canadian neonatal intensive care units (NICUs).

STUDY DESIGN

Data were obtained from the Canadian Neonatal Network and Canadian Neonatal Follow-up Network databases for infants born at <29 weeks of gestation admitted to NICUs from April 2009 to September 2011. Rates of death, severe neurodevelopmental impairment (NDI), and overall NDI were compared between outborn and inborn infants at 18-21 months of age, corrected for prematurity.

RESULTS

Of 2951 eligible infants, 473 (16%) were outborn. Mean birth weight (940 ± 278 g vs 897 + 237 g), rates of treatment with antenatal steroids (53.9% vs 92.9%), birth weight small for gestational age (5.3% vs 9.4%), and maternal college education (43.7% vs 53.9%) differed between outborn and inborn infants, respectively (all P values <.01). The median Score for Neonatal Acute Physiology-II (P = .01) and Apgar score at 5 minutes (P < .01) were higher in inborn infants. Severe brain injury was more common among outborn infants (25.3% vs 14.7%, P < .01). Outborn infants had higher odds of death or severe NDI (aOR 1.7, 95% CI 1.3-2.2), death or overall NDI (aOR 1.6, 95% CI 1.2-2.2), death (aOR 2.1, 95% CI 1.5-3.0), and cerebral palsy (aOR 1.9, 95% CI 1.1-3.3).

CONCLUSIONS

The composite outcomes of death or neurodevelopmental impairment were significantly higher in outborn compared with inborn infants admitted to Canadian NICUs. Adverse outcomes were mainly attributed to increased mortality and cerebral palsy in outborn neonates.

Association between birth route and late-onset sepsis in very preterm neonates

OBJECTIVE

To evaluate the association between birth route and late-onset sepsis (LOS), and coagulase-negative Staphylococcal (CONS)-related LOS in preterm neonates.

STUDY DESIGN

In this observational study, data from 20,038 infants born between 22 and 32 weeks' gestation and admitted to Canadian neonatal intensive care units between 2010 and 2014 were analyzed retrospectively. The impact of birth route on LOS was assessed using univariate analysis and multiple logistic regression.

RESULTS

A total of 8218 neonates were born via vaginal route and 11,820 via cesarean section. Incidence rates of LOS for infants born vaginally and via a cesarean section were 13.1 and 13.2%, respectively, and there was no significant difference in odds of LOS between the groups (adjusted odds ratio (AOR): 0.99; 95% CI 0.87 to 1.12); however, the odds of CONS sepsis were higher in the cesarean group (AOR: 1.15; 95% CI: 1.01 to 1.32).

CONCLUSION

Birth route did not have an impact on LOS, but was associated with CONS-related LOS.

The role of antenatal corticosteroids in twin pregnancies complicated by preterm birth

BACKGROUND

Data regarding the effects of antenatal corticosteroids in twin pregnancies are limited because of the insufficient number of women with twins enrolled in randomized controlled trials on antenatal corticosteroids. Furthermore, the interpretation of available data is limited by the fact that the interval from the administration of antenatal corticosteroids to delivery is greater than 7 days in a large proportion of twins, a factor that has been shown to affect the efficacy of antenatal corticosteroids and has not been controlled for in previous studies.

OBJECTIVE

The objective of the study was to compare neonatal mortality and morbidity in preterm twins receiving a complete course of antenatal corticosteroids 1-7 days before birth to those who did not receive antenatal corticosteroids and to compare these outcome effects with those observed in singletons.

STUDY DESIGN

We performed a retrospective cohort study using data collected on singleton and twin neonates born between 24(0/7) and 33(6/7) weeks' gestational age and were admitted to tertiary neonatal units in Canada between 2010 and 2014. A comparison of neonatal outcomes between twin neonates who received a complete course of antenatal corticosteroids 1-7 days before birth (n = 1758) and those who did not receive antenatal corticosteroids (n = 758) and between singleton neonates who received a complete course of antenatal corticosteroids 1-7 days before birth (n = 4638) and those did not receive antenatal corticosteroids (n = 2312) was conducted after adjusting for gestational age, sex, hypertension, outborn status, small for gestational age, parity, and cesarean birth. Adjusted odds ratios and 95% confidence intervals for various neonatal outcomes were calculated.

RESULTS

Administration of a complete course of antenatal corticosteroids within 1-7 days before birth in both twins and singletons was associated with similar reduced odds of neonatal death (for twins adjusted odds ratio 0.42 [95% confidence interval, 0.24-0.76] and for singletons adjusted odds ratios, 0.38 [95% confidence interval, 0.28-0.50]; P = .7 for comparison of twins vs singletons), mechanical ventilation (for twins adjusted odds ratio, 0.47 [95% confidence interval, 0.35-0.63] and for singletons adjusted odds ratio, 0.47 [95% confidence interval, 0.41-0.55]; P = .9), respiratory distress syndrome (for twins adjusted odds ratio, 0.53 [95% confidence interval, 0.40-0.69], and for singletons adjusted odds ratio, 0.54 [95% confidence interval, 0.47-0.62]; P = .9) and severe neurological injury (for twins adjusted odds ratio, 0.50 [95% confidence interval, 0.30-0.83] and for singletons adjusted odds ratio, 0.45 [95% confidence interval, 0.34-0.59]; P = .7). Administration of a complete course of antenatal corticosteroids was not associated with a reduced odds of bronchopulmonary dysplasia, severe retinopathy of prematurity, or necrotizing enterocolitis in both twins and singletons.

CONCLUSION

Administration of a complete course of antenatal corticosteroids 1-7 days before birth in twin pregnancies is associated with a clinically significant decrease in neonatal mortality, short-term respiratory morbidity, and severe neurological injury that is similar in magnitude to that observed among singletons.

Hemolytic disease of the newborn caused by anti-Wright (anti-Wra): case report and review of literature

Antibodies to red cell antigens that are found at low frequency in the general population are rare causes of hemolytic disease of the newborn. To understand how to detect these cases, we provide a basic review of routine antenatal maternal antibody testing and report a case of a neonate with severe HDN caused by anti-Wright (anti-Wra), successfully managed with transfusion, phototherapy, and high-dose intravenous immunoglobulin. When hemolysis in a newborn is suspected in the absence of major blood group incompatibility or commonly detected maternal red cell antibodies, a direct antiglobulin test should be performed. A positive DAT should alert the clinician to the presence of maternal antibodies against low-incidence antigens. Antibodies to the Wra antigen are one such rare cause of HDN.

Use of a dual-labelled oligonucleotide as a DNA dosemeter for radiological exposure detection

A reporter molecule consisting of a synthetic oligonucleotide is being characterised for a novel damage detection scenario for its potential use as a field-deployable, personal deoxyribonucleic acid (DNA) dosemeter for radiation detection. This dosemeter is devoid of any biological properties other than being naked DNA and therefore has no DNA repair capabilities. It supports biodosimetry techniques, which require lengthy analysis of cells from irradiated individuals, and improves upon inorganic dosimetry, thereby providing for a more relevant means of measuring the accumulated dose from a potentially mixed-radiation field. Radiation-induced single strand breaks (SSBs) within the DNA result in a quantifiable fluorescent signal. Proof of concept has been achieved over 250 mGy-10 Gy dose range in radiation fields from ⁶⁰Co, with similar results seen using a linear accelerator X-ray source. Further refinements to both the molecule and the exposure/detection platform are expected to lead to enhanced levels of detection for mixed-field radiological events.

Factors affecting protein release from alginate-chitosan coacervate microcapsules during production and gastric/intestinal simulation

A series of experiments was performed to evaluate the influence of a number of physico-chemical factors on the diffusion of a model protein, bovine serum albumin (BSA), from dried chitosan-coated alginate microcapsules. Diffusion of BSA was quantified during the microcapsule manufacture processes (gelation, washing, rinsing) and during incubation in conditions simulating the pH encountered during the gastric (0.1 N HCl; pH 1.5) and intestinal (200 mM Tris-HCl; pH 7.5) phases of digestion. Factors tested included alginate and chitosan concentration, calcium chloride (CaCl2) concentration in the gelation medium, loading rate, chitosan molecular mass and pH of the gelation medium. Microcapsule size and gelation time were altered in order to determine their effects on protein retention. Alginate and chitosan concentration significantly influenced BSA retention during microcapsule manufacture and acid incubation, as did calcium chloride concentration in the gelation medium (P<0.05). BSA retention during manufacture was not significantly altered by protein loading rate or pH of the encapsulation medium, however, protein retention during acid incubation decreased significantly with increasing protein loading rate and encapsulation medium pH (P<0.05). Microcapsules that were washed with acetone following manufacture demonstrated significantly increased protein retention during acid incubation (P<0.05). In microcapsules that had been acetone-dried to a point whereby their mass was reduced to 10% of that immediately following encapsulation, protein retention was over 80% following 24-h acid incubation vs. only 20% protein retention from non acetone-dried microcapsules. The presence of calcium in the neutral buffer medium significantly reduced BSA diffusion in a concentration-dependent manner (P<0.05).