Priorities, opportunities, and challenges for integrating microorganisms into Earth system models for climate change prediction

Climate change jeopardizes human health, global biodiversity, and sustainability of the biosphere. To make reliable predictions about climate change, scientists use Earth system models (ESMs) that integrate physical, chemical, and biological processes occurring on land, the oceans, and the atmosphere. Although critical for catalyzing coupled biogeochemical processes, microorganisms have traditionally been left out of ESMs. Here, we generate a "top 10" list of priorities, opportunities, and challenges for the explicit integration of microorganisms into ESMs. We discuss the need for coarse-graining microbial information into functionally relevant categories, as well as the capacity for microorganisms to rapidly evolve in response to climate-change drivers. Microbiologists are uniquely positioned to collect novel and valuable information necessary for next-generation ESMs, but this requires data harmonization and transdisciplinary collaboration to effectively guide adaptation strategies and mitigation policy.

Severe Neonatal Opioid Withdrawal Requiring Pharmacotherapy: Impact of Region of Residence

OBJECTIVES

 Our objective was to evaluate the trend and to assess the impact of maternal region of residence in Western New York (WNY), on severe neonatal opioid withdrawal syndrome (NOWS).

STUDY DESIGN

 Term infants' born at gestational age greater than or equal to 37 weeks with severe NOWS, defined as withdrawal resulting in the receipt of pharmacologic therapy from WNY admitted to our neonatal intensive care unit (NICU) from January 1, 2008 to December 31, 2016, were included. Severe NOWS admissions to our NICU from the following five regions were controlled with birth and insurance data: (1) Urban North, (2) Erie Coastal, (3) Niagara Frontier, (4) Southern Tier, and (5) Urban South.

RESULTS

 "Urban South" residence was associated with an increased risk of severe NOWS (adjusted odds ratio = 1.8, 97.5% confidence interval: 1.1-2.9). The trend in admission for severe NOWS doubled between 2008 to 2010 and 2014 to 2016 (p = 0.01). More infants born to maternal nonprescribed opioid users were placed in foster care at discharge (36.5 vs. 1.9%, p < 0.001).

CONCLUSION

 In WNY, neonates born to mothers from the "Urban South" were twice at risk of being admitted for severe NOWS. One-third of infants with severe NOWS after nonprescribed opioid use were placed in foster care. Implementing targeted strategies at the community level may help improve outcomes in NOWS.

KEY POINTS

· Maternal region of residence is a risk factor for severe neonatal opioid withdrawal.. · Admissions for severe neonatal opioid withdrawal trended up from 2008 to 2010 to 2014 to 2016.. · One-third of the infants born to mothers on nonprescribed opioids were discharged to foster care..

Less Invasive Surfactant Administration: A Viewpoint

The standard of care in treating respiratory distress syndrome in preterm infants is respiratory support with nasal continuous positive airway pressure or a combination of continuous positive airway pressure and exogenous surfactant replacement. Endotracheal intubation, the conventional method for surfactant administration, is an invasive procedure associated with procedural and mechanical ventilation complications. The INSURE (intubation, surfactant administration, and extubation soon after) technique is an accepted method aimed at reducing the short-term complications and long-term morbidities related to mechanical ventilation but does not eliminate risks associated with endotracheal intubation and mechanical ventilation. Alternative methods of surfactant delivery that can overcome the problems associated with the INSURE technique are surfactant through a laryngeal mask, surfactant through a thin intratracheal catheter, and aerosolized surfactant delivered using nebulizers. The three alternative methods of surfactant delivery studied in the last two decades have advantages and limitations. More than a dozen randomized controlled trials have aimed to study the benefits of the three alternative techniques of surfactant delivery compared with INSURE as the control arm, with promising results in terms of reduction in mortality, need for mechanical ventilation, and bronchopulmonary dysplasia. The need to find a less invasive surfactant administration technique is a clinically relevant problem. Before broader adoption in routine clinical practice, the most beneficial technique among the three alternative strategies should be identified. This review aims to summarize the current evidence for using the three alternative techniques of surfactant administration in neonates, compare the three techniques, highlight the knowledge gaps, and suggest future directions. KEY POINTS: · The need to find a less invasive alternative method of surfactant delivery is a clinically relevant problem.. · Clinical trials that have studied alternative surfactant delivery methods have shown promising results but are inconclusive for broader adoption into clinical practice.. · Future studies should explore novel clinical trial methodologies and select clinically significant long term outcomes for comparison..

Femoral Occlusion during Neonatal Cardiopulmonary Resuscitation Improves Outcomes in an Ovine Model of Perinatal Cardiac Arrest

BACKGROUND

The goal of chest compressions during neonatal resuscitation is to increase cerebral and coronary blood flow leading to the return of spontaneous circulation (ROSC). During chest compressions, bilateral femoral occlusion may increase afterload and promote carotid and coronary flow, an effect similar to epinephrine. Our objectives were to determine the impact of bilateral femoral occlusion during chest compressions on the incidence and timing of ROSC and hemodynamics.

METHODOLOGY

In this randomized study, 19 term fetal lambs in cardiac arrest were resuscitated based on the Neonatal Resuscitation Program guidelines and randomized into two groups: femoral occlusion or controls. Bilateral femoral arteries were occluded by applying pressure using two fingers during chest compressions.

RESULTS

Seventy percent (7/10) of the lambs in the femoral occlusion group achieved ROSC in 5 ± 2 min and three lambs (30%) did not receive epinephrine. ROSC was achieved in 44% (4/9) of the controls in 13 ± 6 min and all lambs received epinephrine. The femoral occlusion group had higher diastolic blood pressures, carotid and coronary blood flow.

CONCLUSION

Femoral occlusion resulted in faster and higher incidence of ROSC, most likely due to attaining increased diastolic pressures, coronary and carotid flow. This is a low-tech intervention that can be easily adapted in resource limited settings, with the potential to improve survival and neurodevelopmental outcomes.

Masked Randomized Trial of Epinephrine versus Vasopressin in an Ovine Model of Perinatal Cardiac Arrest

BACKGROUND

Current neonatal resuscitation guidelines recommend the use of epinephrine for bradycardia/arrest not responding to ventilation and chest compressions. Vasopressin is a systemic vasoconstrictor and is more effective than epinephrine in postnatal piglets with cardiac arrest. There are no studies comparing vasopressin with epinephrine in newly born animal models with cardiac arrest induced by umbilical cord occlusion. Objective: To compare the effect of epinephrine and vasopressin on the incidence and time to return of spontaneous circulation (ROSC), hemodynamics, plasma drug levels, and vasoreactivity in perinatal cardiac arrest. Design/Methods: Twenty-seven term fetal lambs in cardiac arrest induced by cord occlusion were instrumented and resuscitated following randomization to epinephrine or vasopressin through a low umbilical venous catheter. Results: Eight lambs achieved ROSC prior to medication. Epinephrine achieved ROSC in 7/10 lambs by 8 ± 2 min. Vasopressin achieved ROSC in 3/9 lambs by 13 ± 6 min. Plasma vasopressin levels in nonresponders were much lower than responders after the first dose. Vasopressin caused in vivo increased pulmonary blood flow and in vitro coronary vasoconstriction. Conclusions: Vasopressin resulted in lower incidence and longer time to ROSC compared to epinephrine in a perinatal model of cardiac arrest supporting the current recommendations for exclusive use of epinephrine in neonatal resuscitation.

Initial Use of 100% but Not 60% or 30% Oxygen Achieved a Target Heart Rate of 100 bpm and Preductal Saturations of 80% Faster in a Bradycardic Preterm Model

Background: Currently, 21−30% supplemental oxygen is recommended during resuscitation of preterm neonates. Recent studies have shown that 58% of infants < 32 week gestation age are born with a heart rate (HR) < 100 bpm. Prolonged bradycardia with the inability to achieve a preductal saturation (SpO2) of 80% by 5 min is associated with mortality and morbidity in preterm infants. The optimal oxygen concentration that enables the achievement of a HR ≥ 100 bpm and SpO2 of ≥80% by 5 min in preterm lambs is not known. Methods: Preterm ovine model (125−127 d, gestation equivalent to human neonates < 28 weeks) was instrumented, and asphyxia was induced by umbilical cord occlusion until bradycardia. Ventilation was initiated with 30% (OX30), 60% (OX60), and 100% (OX100) for the first 2 min and titrated proportionately to the difference from the recommended preductal SpO2. Our primary outcome was the incidence of the composite of HR ≥ 100 bpm and SpO2 ≥ 80%, by 5 min. Secondary outcomes were to evaluate the time taken to achieve the primary outcome, gas exchange, pulmonary/systemic hemodynamics, and the oxidative injury. Results: Eighteen lambs (OX30-6, OX60-5. OX100-7) had an average HR < 91 bpm with a pH of <6.92 before resuscitation. Sixty seven percent achieved the primary outcome in OX100, 40% in OX60, and none in OX30. The time taken to achieve the primary outcome was significantly shorter with OX100 (6 ± 2 min) than with OX30 (10 ± 3 min) (* p = 0.04). The preductal SpO2 was highest with OX100, while the peak pulmonary blood flow was lowest with OX30, with no difference in O2 delivery to the brain or oxidative injury by 10 min. Conclusions: The use of 30%, 60%, and 100% supplemental O2 in a bradycardic preterm ovine model did not demonstrate a significant difference in the composite primary outcome. The current recommendation to use 30% oxygen did not achieve a preductal SpO2 of 80% by 5 min in any preterm lambs. Clinical studies to optimize supplemental O2 in depressed preterm neonates not requiring chest compressions are warranted.

Placental transfusion during neonatal resuscitation in an asphyxiated preterm model

BACKGROUND

Neonatal Resuscitation Program does not recommend placental transfusion in depressed preterm neonates.

METHODS

Our objectives were to study the effect of delayed cord clamping (DCC) with ventilation for 5 min (DCCV, n-5), umbilical cord milking (UCM) without ventilation (n-6), UCM with ventilation (UCMV, n-6), early cord clamping followed by ventilation (ECCV, n-6) on red cell volume (RCV), and hemodynamic changes in asphyxiated preterm lambs. Twenty-three preterm lambs at 127-128 days gestation were randomized to DCCV, UCM, UCMV, and ECCV. We defined asphyxia as heart rate <100/min.

RESULTS

The UCMV had the highest neonatal RCV as a percentage of fetoplacental volume compared to the other groups (UCMV 85.5 ± 10%, UCM 72 ± 10%, ECCV 65 ± 14%, DCCV 61 ± 10%, p < 0.01). The DCCV led to better ventilation (66 ± 1 mmHg) and higher pulmonary blood flow (75 ± 24 ml/kg/min). The carotid flow was significantly higher in UCM without ventilation. The fluctuations in carotid flow with milking were 25 ± 6% higher from baseline during UCM, compared to 6 ± 3% in UCMV (p < 0.01).

CONCLUSIONS

Cord milking with ventilation led to higher RCV than other interventions. Ventilation during cord milking reduced fluctuation in carotid flow compared to UCM alone. DCCV led to better ventilation and pulmonary blood flow but did not increase RCV.

IMPACT

The best practice of placental transfusion in a depressed preterm neonate remains unknown. Ventilation with an intact cord improves gas exchange and hemodynamics in an asphyxiated preterm model. Cord milking without ventilation led to lower red cell volume but higher carotid blood flow fluctuations compared to milking with ventilation. Our data can be translated to bedside and could impact preterm resuscitation.

Pulmonary hypertension and oxidative stress: Where is the link?

Oxidative stress can be associated with hyperoxia and hypoxia and is characterized by an increase in reactive oxygen (ROS) and nitrogen (RNS) species generated by an underlying disease process or by supplemental oxygen that exceeds the neutralization capacity of the organ system. ROS and RNS acting as free radicals can inactive several enzymes and vasodilators in the nitric oxide pathway promoting pulmonary vasoconstriction resulting in persistent pulmonary hypertension of the newborn (PPHN). Studies in animal models of PPHN have shown high ROS/RNS that is further increased by hyperoxic ventilation. In addition, antioxidant therapy increased PaO2 in these models, but clinical trials are lacking. We recommend targeting preductal SpO2 between 90 and 97%, PaO2 between 55 and 80 mmHg and avoiding FiO2 > 0.6-0.8 if possible during PPHN management. This review highlights the role of oxidative and nitrosative stress markers on PPHN and potential therapeutic interventions that may alleviate the consequences of increased oxidant stress during ventilation with supplemental oxygen.

Laryngeal Masks in Neonatal Resuscitation-A Narrative Review of Updates 2022

Positive pressure ventilation (PPV) is crucial to neonatal cardiopulmonary resuscitation because respiratory failure precedes cardiac failure in newborns affected by perinatal asphyxia. Prolonged ineffective PPV could lead to a need for advanced resuscitation such as intubation, chest compression, and epinephrine. Every 30 s delay in initiation of PPV increased the risk of death or morbidity by 16%. The most effective interface for providing PPV in the early phases of resuscitation is still unclear. Laryngeal masks (LMs) are supraglottic airway devices that provide less invasive and relatively stable airway access without the need for laryngoscopy which have been studied as an alternative to face masks and endotracheal tubes in the initial stages of neonatal resuscitation. A meta-analysis found that LM is a safe and more effective alternative to face mask ventilation in neonatal resuscitation. LM is recommended as an alternative secondary airway device for the resuscitation of infants > 34 weeks by the International Liaison Committee on Resuscitation. It is adopted by various national neonatal resuscitation guidelines across the globe. Recent good-quality randomized trials have enhanced our understanding of the utility of laryngeal masks in low-resource settings. Nevertheless, LM is underutilized due to its variable availability in delivery rooms, providers’ limited experience, insufficient training, preference for endotracheal tube, and lack of awareness.

Randomised trial of epinephrine dose and flush volume in term newborn lambs

OBJECTIVES

Neonatal resuscitation guidelines recommend 0.5-1 mL saline flush following 0.01-0.03 mg/kg of epinephrine via low umbilical venous catheter for persistent bradycardia despite effective positive pressure ventilation (PPV) and chest compressions (CC). We evaluated the effects of 1 mL vs 3 mL/kg flush volumes and 0.01 vs 0.03 mg/kg doses on return of spontaneous circulation (ROSC) and epinephrine pharmacokinetics in lambs with cardiac arrest.

DESIGN

Forty term lambs in cardiac arrest were randomised to receive 0.01 or 0.03 mg/kg epinephrine followed by 1 mL or 3 mL/kg flush after effective PPV and CC. Epinephrine (with 1 mL flush) was repeated every 3 min until ROSC or until 20 min. Haemodynamics, blood gases and plasma epinephrine concentrations were monitored.

RESULTS

Ten lambs had ROSC before epinephrine administration and 2 died during instrumentation. Among 28 lambs that received epinephrine, 2/6 in 0.01 mg/kg-1 mL flush, 3/6 in 0.01 mg/kg-3 mL/kg flush, 5/7 in 0.03 mg/kg-1 mL flush and 9/9 in 0.03 mg/kg-3 mL/kg flush achieved ROSC (p=0.02). ROSC was five times faster with 0.03 mg/kg epinephrine compared with 0.01 mg/kg (adjusted HR (95% CI) 5.08 (1.7 to 15.25)) and three times faster with 3 mL/kg flush compared with 1 mL flush (3.5 (1.27 to 9.71)). Plasma epinephrine concentrations were higher with 0.01 mg/kg-3 mL/kg flush (adjusted geometric mean ratio 6.0 (1.4 to 25.7)), 0.03 mg/kg-1 mL flush (11.3 (2.1 to 60.3)) and 0.03 mg/kg-3 mL/kg flush (11.0 (2.2 to 55.3)) compared with 0.01 mg/kg-1 mL flush.

CONCLUSIONS

0.03 mg/kg epinephrine dose with 3 mL/kg flush volume is associated with the highest ROSC rate, increases peak plasma epinephrine concentrations and hastens time to ROSC. Clinical trials evaluating optimal epinephrine dose and flush volume are warranted.

Sustained Inflation Reduces Pulmonary Blood Flow during Resuscitation with an Intact Cord

The optimal timing of cord clamping in asphyxia is not known. Our aims were to determine the effect of ventilation (sustained inflation-SI vs. positive pressure ventilation-V) with early (ECC) or delayed cord clamping (DCC) in asphyxiated near-term lambs. We hypothesized that SI with DCC improves gas exchange and hemodynamics in near-term lambs with asphyxial bradycardia. A total of 28 lambs were asphyxiated to a mean blood pressure of 22 mmHg. Lambs were randomized based on the timing of cord clamping (ECC-immediate, DCC-60 s) and mode of initial ventilation into five groups: ECC + V, ECC + SI, DCC, DCC + V and DCC + SI. The magnitude of placental transfusion was assessed using biotinylated RBC. Though an asphyxial bradycardia model, 2-3 lambs in each group were arrested. There was no difference in primary outcomes, the time to reach baseline carotid blood flow (CBF), HR ≥ 100 bpm or MBP ≥ 40 mmHg. SI reduced pulmonary (PBF) and umbilical venous (UV) blood flow without affecting CBF or umbilical arterial blood flow. A significant reduction in PBF with SI persisted for a few minutes after birth. In our model of perinatal asphyxia, an initial SI breath increased airway pressure, and reduced PBF and UV return with an intact cord. Further clinical studies evaluating the timing of cord clamping and ventilation strategy in asphyxiated infants are warranted.

Proficiency of Laryngeal Mask Airway Insertion Skill in NRP Certified Providers

OBJECTIVE

In 2015, Neonatal Resuscitation Program (NRP) recommended laryngeal mask airway (LMA) as an alternative to the endotracheal tube (ETT) in situations where the provider is "unable to intubate and unable to ventilate." LMA insertion is being taught in the NRP routinely. However, endotracheal intubation is the primary method considered as the standard of care in neonatal resuscitation. LMA insertion is a relatively simple procedure with an average insertion time of < 10 seconds. Newer generation LMA can have the added advantage of reducing the risk of aerosol generation and improving the safety of the providers. Only a few recent studies have evaluated the LMA insertion skills of neonatal resuscitation providers. We wanted to study the proficiency of NRP providers in the technique of LMA insertion. We hypothesized that NRP providers would have LMA insertion skills equivalent to the standard of care (ETT insertion).

STUDY

DESIGN:  A manikin-based study was done from July 2019 to December 2019. We enrolled 31 NRP providers with 1 or more years since the first certification and current valid NRP provider/instructor status. The participants were instructed to insert an ETT and LMA in the manikin. The procedures were video recorded. The time taken to insert and start ventilation with each device, including the number of attempts for successful insertion, was noted. A Likert scale questionnaire was filled by each participant indicating the level of confidence, perception of ease, and the ability to provide effective positive pressure ventilation (PPV) with each of the procedures. The paired t-test, chi-square test, and Kruskal-Wallis' test were used for the statistical analysis.

RESULTS

Eight (25.8%) out of the 31 participants failed to insert any one of the devices. So, 23 providers were analyzed for the outcomes. We found that the mean duration taken to insert the ETT and LMA was not statistically different (32 vs. 36 seconds). LMA insertion had a higher failure rate compared with ETT. Providers did not perceive confidence to insert LMA when compared with ETT. They did not recognize LMA insertion as a more effortless procedure relative to endotracheal intubation. The providers felt that their ability to provide effective PPV using LMA was inferior to ETT.

CONCLUSION

The NRP certified providers in this study did not demonstrate proficiency in the insertion of LMA equivalent to the endotracheal intubation.

KEY POINTS

· LMA insertion skill was studied in NRP providers using a manikin.. · Providers had a higher frequency of failure in inserting LMA compared to ETT.. · Providers' perceived confidence and effectiveness of the LMA procedure were inferior to ETT..

Optimal Oxygen Targets in Term Lambs with Meconium Aspiration Syndrome and Pulmonary Hypertension

Optimal oxygen saturation as measured by pulse oximetry (SpO2) in neonatal lung injury, such as meconium aspiration syndrome (MAS) and persistent pulmonary hypertension of newborn (PPHN), is not known. Our goal was to determine the SpO2 range in lambs with MAS and PPHN that results in the highest brain oxygen delivery (bDO2) and pulmonary blood flow (Qp) and the lowest pulmonary vascular resistance and oxidative stress. Meconium was instilled into endotracheal tubes in 25 near-term gestation lambs, and the umbilical cord was occluded to induce asphyxia and gasping, causing MAS and PPHN. Lambs were randomized into four groups and ventilated for 6 hours with fixed fraction of inspired oxygen (FiO2) = 1.0 irrespective of SpO2, and three groups had FiO2 titrated to keep preductal SpO2 between 85% and 89%, 90% and 94%, and 95% and 99%, respectively. Tissues were collected to measure nitric oxide synthase activity, 3-nitrotyrosine, and 8-isoprostanes. Throughout the 6-hour exposure period, lambs in the 95-99% SpO2 target group had the highest Qp, lowest pulmonary vascular resistance, and highest bDO2 but were exposed to higher FiO2 (0.5 ± 0.21 vs. 0.29 ± 0.17) with higher lung 3-nitrotyrosine (0.67 [interquartile range (IQR), 0.43-0.73] ng/mcg protein vs. 0.1 [IQR, 0.09-0.2] ng/mcg protein) and lower lung nitric oxide synthase activity (196 [IQR, 192-201] mMol nitrite/mg protein vs. 270 [IQR, 227-280] mMol nitrite/mg protein) compared with the 90-94% target group. Brain 3-nitrotyrosine was lower in the 85-89% target group, and brain/lung 8-isoprostane levels were not significantly different. In term lambs with MAS and PPHN, Qp and bDO2 through the first 6 hours are higher with target SpO2 in the 95-99% range. However, the 90-94% target range is associated with significantly lower FiO2 and lung oxidative stress. Clinical trials comparing the 90-94% versus the 95-99% SpO2 target range in term infants with PPHN are warranted.

COVID-19 in Newborns and Infants-Low Risk of Severe Disease: Silver Lining or Dark Cloud?

One hundred years after the 1918 influenza pandemic, we now face another pandemic with the severe acute respiratory syndrome-novel coronavirus-2 (SARS-CoV-2). There is considerable variability in the incidence of infection and severe disease following exposure to SARS-CoV-2. Data from China and the United States suggest a low prevalence of neonates, infants, and children, with those affected not suffering from severe disease. In this article, we speculate different theories why this novel agent is sparing neonates, infants, and young children. The low severity of SARS-CoV-2 infection in this population is associated with a high incidence of asymptomatic or mildly symptomatic infection making them efficient carriers. KEY POINTS: · There is a low prevalence of novel coronavirus disease in neonates, infants, and children.. · The fetal hemoglobin may play a protective role against coronavirus in neonates.. · Immature angiotensin converting enzyme (ACE2) interferes with coronavirus entry into the cells..

Perinatal Hypophosphatasia in a Premature Infant

A premature male infant was delivered at 32 weeks' gestation due to category-2 fetal tracing after preterm labor. The physical exam showed shortened and bowed long bones, with calvarium felt in small area of the head. Serum alkaline phosphatase was very low on admission. Extensive metaphyseal abnormalities, bowing of long bones, and poor ossification of all bones were noted on skeletal survey (radiography). Based on ultrasound evidence of "bowing" and long bone fractures at 26 weeks, amniocentesis was performed that later diagnosed hypophosphatasia by genetic testing while ruling out osteogenesis imperfecta. Although ventilated initially, the infant gradually improved with enzyme replacement therapy (ERT) and was extubated to noninvasive ventilation for 6 weeks. Following clinical deterioration with hypoxic respiratory failure secondary to sepsis at 4 months of age, he succumbed to severe pulmonary hypertension, likely secondary to chronic lung disease and prolonged ventilation. Early diagnosis allowed timely initiation of appropriate therapy. Radiological improvement with the therapy showed promising results in this rare disease. Despite specific novel therapy being available, variability in presentation dictates prognosis in this previously universally fatal condition. The potential unknown effects of ERT on pulmonary vascular remodeling need further investigation.

Epinephrine in Neonatal Resuscitation

Epinephrine is the only medication recommended by the International Liaison Committee on Resuscitation for use in newborn resuscitation. Strong evidence from large clinical trials is lacking owing to the infrequent use of epinephrine during neonatal resuscitation. Current recommendations are weak as they are extrapolated from animal models or pediatric and adult studies that do not adequately depict the transitioning circulation and fluid-filled lungs of the newborn in the delivery room. Many gaps in knowledge including the optimal dosing, best route and timing of epinephrine administration warrant further studies. Experiments on a well-established ovine model of perinatal asphyxial cardiac arrest closely mimicking the newborn infant provide important information that can guide future clinical trials.

Bioavailability of endotracheal epinephrine in an ovine model of neonatal resuscitation

BACKGROUND

Distressed infants in the delivery room and those that have completed postnatal transition are both resuscitated according to established neonatal resuscitation guidelines, often with endotracheal (ET) epinephrine at the same dose. We hypothesized that ET epinephrine would have higher bioavailability in a post-transitional compared to transitioning newborn model due to absence of fetal lung liquid and intra-cardiac shunts.

METHODS

15 term fetal (transitioning newborn) and 6 postnatal lambs were asphyxiated by umbilical cord and ET tube occlusion respectively. Lambs were resuscitated after 5 min of asystole. ET epinephrine (0.1 mg/kg) was administered after 1 min of positive pressure ventilation (PPV) and chest compressions, and repeated 3 min later, followed by intravenous (IV) epinephrine (0.03 mg/kg) every 3 min until return of spontaneous circulation (ROSC). Serial plasma epinephrine concentrations were measured.

RESULTS

Peak plasma epinephrine concentrations were lower in transitioning newborns as compared to postnatal lambs: after a single ET dose (145.36 ± 135.5 ng/ml vs 553.54 ± 215 ng/ml, p < 0.01) and after two ET doses (443 ± 192.49 ng/ml vs 1406 ± 420.8 ng/ml, p < 0.01). The rates of ROSC with a single ET dose were similar in both groups (40% vs 50% in newborn and postnatal respectively, p > 0.99). There was a higher incidence of post-ROSC tachycardia and increased carotid blood flow in the postnatal group.

CONCLUSIONS

In the postnatal period, ET epinephrine at currently recommended doses resulted in higher peak epinephrine concentrations, post-ROSC tachycardia and cerebral reperfusion without significant differences in incidence of ROSC. Further studies evaluating the optimal dose of ET epinephrine during the postnatal period are warranted.

Natural drugs, not so natural effects: Neonatal abstinence syndrome secondary to 'kratom'

BACKGROUND

Mitragyna speciosa, also known as kratom, is obtained from the coffee plant family 'Rubiaceae.' Kratom is available in the form of capsules, whole, processed and powdered leaves, and as liquids. Secondary to its 'natural herb' status and opioid effects, it is misconceived to be a safe alternative for the treatment of chronic pain. The use of kratom has increased by tenfold in the United States since 2010.

METHODS AND RESULTS

We report a term neonate who was born to a chronic kratom user and required treatment with opiates for neonatal drug withdrawal.

CONCLUSION

Physicians should be aware of these herbal supplements and its potential withdrawal effects in newborn which cannot be picked up by the standard toxicology screen.

Effect of various inspired oxygen concentrations on pulmonary and systemic hemodynamics and oxygenation during resuscitation in a transitioning preterm model

BACKGROUND

The Neonatal Resuscitation Program recommends initial resuscitation of preterm infants with low oxygen (O₂) followed by titration to target preductal saturations (SpO₂). We studied the effect of resuscitation with titrated O₂ on gas exchange, pulmonary, and systemic hemodynamics.

METHODOLOGY

Twenty-nine preterm lambs (127 d gestation) were randomized to resuscitation with 21% O₂ (n = 7), 100% O₂ (n = 6), or initiation at 21% and titrated to target SpO₂ (n = 16). Seven healthy term control lambs were ventilated with 21% O₂.

RESULTS

Preductal SpO₂ achieved by titrating O₂ was within the desired range similar to term lambs in 21% O₂. Resuscitation of preterm lambs with 21% and 100% O₂ resulted in SpO₂ below and above the target, respectively. Ventilation of preterm lambs with 100% O₂ and term lambs with 21% O₂ effectively decreased pulmonary vascular resistance (PVR). In contrast, preterm lambs with 21% O₂ and titrated O₂ demonstrated significantly higher PVR than term lambs on 21% O₂.

CONCLUSION(S)

Initial resuscitation with 21% O₂ followed by titration of O₂ led to suboptimal pulmonary vascular transition at birth in preterm lambs. Ventilation with 100% O₂ in preterm lambs caused hyperoxia but reduced PVR similar to term lambs on 21% O₂. Studies evaluating the initiation of resuscitation at a higher O₂ concentration followed by titration based on SpO₂ in preterm neonates are needed.

Immunization with Salmonella Abortusequi phage lysate protects guinea pig against the virulent challenge of SAE-742

Salmonella Abortusequi causes important clinical diseases in horses possibly leading to abortion. In the present investigation, the protective efficacy of both plain and aluminum hydroxide gel adjuvanted phage lysate was evaluated in guinea pig model. Broad host range bacteriophage P_IZ-SAE-2, was characterized and used for generation of lysates. Three different lysate batches, produced through separate cycles and characterized, were pooled together for immunization study. Plain and adjuvanted phage lysate preparations elicited both humoral and cellmediated immunity. The adjuvanted lysate at a dose of 50 μl elicited the highest protective efficacy against direct challenge at 28th DPI. Thus, the present study describes a new method of bacterial inactivation for producing a new class of better & safe immunprophylactic agents. This is the first report of producing an inactivated vaccine candidate using a new approach against equine salmonellosis.

The Perinatal Asphyxiated Lamb Model: A Model for Newborn Resuscitation

Birth asphyxia accounts for nearly one million deaths worldwide each year, and is one of the primary causes of early neonatal morbidity and mortality. Many aspects of the current neonatal resuscitation guidelines remain controversial given the difficulties in conducting randomized clinical trials owing to the infrequent and often unpredictable need for extensive resuscitation. Most studies on neonatal resuscitation stem from manikin models that fail to truly reflect physiologic changes or piglet models that have cleared their lung fluid and that have completed the transition from fetal to neonatal circulation. The present protocol provides a detailed step-by-step description on how to create a perinatal asphyxiated fetal lamb model. The proposed model has a transitioning circulation and fluid-filled lungs, which mimics human newborns following delivery, and is, therefore, an excellent animal model to study newborn physiology. An important limitation to lamb experiments is the higher associated cost.

Approach to Infants Born Through Meconium Stained Amniotic Fluid: Evolution Based on Evidence?

Meconium-stained amniotic fluid (MSAF) during delivery is a marker of fetal stress. Neonates born through MSAF often need resuscitation and are at risk of meconium aspiration syndrome (MAS), air leaks, hypoxic-ischemic encephalopathy, extracorporeal membrane oxygenation (ECMO), and death. The neonatal resuscitation approach to MSAF has evolved over the last three decades. Previously, nonvigorous neonates soon after delivery were suctioned under the vocal cords with direct visualization technique using a meconium aspirator. The recent neonatal resuscitation program (NRP) recommends against suctioning but favors resuscitation with positive pressure ventilation of nonvigorous neonates with MSAF. This recommendation is aimed to prevent delay in resuscitation and minimize hypoxia-ischemia often associated with MSAF. In this review, we discuss the pathophysiology, evolution and the evidence, randomized control trials, observational studies, and translational research to support these recommendations. The frequency of ECMO use for neonatal respiratory indication of MAS has declined over the years probably secondary to improvements in neonatal intensive care and reduction of postmaturity. Changes in resuscitation practices may have contributed to reduced incidence and severity of MAS. Larger randomized controlled studies are needed among nonvigorous infants with MSAF. However, ethical dilemmas and loss of equipoise pose a challenge to conduct such studies.

Apnea, bradycardia and desaturation spells in premature infants: impact of a protocol for the duration of 'spell-free' observation on interprovider variability and readmission rates

OBJECTIVE

To study the impact of implementing a protocol to standardize the duration of observation in preterm infants with apnea/bradycardia/desaturation spells before hospital discharge on length of stay (LOS) and readmission rates.

STUDY DESIGN

A protocol to standardize the duration of in-hospital observation for preterm infants with apnea, bradycardia and desaturation spells who were otherwise ready for discharge was implemented in December 2013. We evaluated the impact of this protocol on the LOS and readmission rates of very low birth weight infants (VLBW). Data on readmission for apnea and an apparent life-threatening event (ALTE) within 30 days of discharge were collected. The pre-implementation epoch (2011 to 2013) was compared to the post-implementation period (2014 to 2016).

RESULTS

There were 426 and 368 VLBW discharges before and after initiation of the protocol during 2011 to 2013 and 2014 to 2016, respectively. The LOS did not change with protocol implementation (66±42 vs 64±42 days before and after implementation of the protocol, respectively). Interprovider variability on the duration of observation for apneic spells (F-8.8, P=0.04) and bradycardia spells (F-17.4, P<0.001) decreased after implementation of the protocol. The readmission rate for apnea/ALTE after the protocol decreased from 12.1 to 3.4% (P=0.01).

CONCLUSION

Implementing an institutional protocol for VLBW infants to determine the duration of apnea/bradycardia/ desaturation spell-free observation period as recommended by the American Academy of Pediatrics clinical report did not prolong the LOS but effectively reduced interprovider variability and readmission rates.

Complications of prematurity: an infographic

Infographics or information graphics are easy-to-understand visual representation of knowledge. An infographic outlining the course of an extremely preterm infant and various potential complications encountered during a neonatal intensive care unit (NICU) stay was developed. This infographic can be used to discuss outcomes of prematurity during prenatal counseling and while the infant is in the NICU.

Hemodynamics and gas exchange during chest compressions in neonatal resuscitation

PURPOSE

Current knowledge about pulmonary/systemic hemodynamics and gas exchange during neonatal resuscitation in a model of transitioning fetal circulation with fetal shunts and fluid-filled alveoli is limited. Using a fetal lamb asphyxia model, we sought to determine whether hemodynamic or gas-exchange parameters predicted successful return of spontaneous circulation (ROSC).

METHODS

The umbilical cord was occluded in 22 lambs to induce asphyxial cardiac arrest. Following five minutes of asystole, resuscitation as per AHA-Neonatal Resuscitation Program guidelines was initiated. Hemodynamic parameters and serial arterial blood gases were assessed during resuscitation.

RESULTS

ROSC occurred in 18 lambs (82%) at a median (IQR) time of 120 (105-180) seconds. There were no differences in hemodynamic parameters at baseline and at any given time point during resuscitation between the lambs that achieved ROSC and those that did not. Blood gases at arrest prior to resuscitation were comparable between groups. However, lambs that achieved ROSC had lower PaO2, higher PaCO2, and lower lactate during resuscitation. Increase in diastolic blood pressures induced by epinephrine in lambs that achieved ROSC (11 ±4 mmHg) did not differ from those that were not resuscitated (10 ±6 mmHg). Low diastolic blood pressures were adequate to achieve ROSC.

CONCLUSIONS

Hemodynamic parameters in a neonatal lamb asphyxia model with transitioning circulation did not predict success of ROSC. Lactic acidosis, higher PaO2 and lower PaCO2 observed in the lambs that did not achieve ROSC may represent a state of inadequate tissue perfusion and/or mitochondrial dysfunction.

Early Use of Inhaled Nitric Oxide in Preterm Infants: Is there a Rationale for Selective Approach?

Background Inhaled nitric oxide (iNO) is being increasingly used in preterm infants < 34 weeks with hypoxemic respiratory failure (HRF) and/or pulmonary hypertension (PH). Objective To evaluate the risk factors, survival characteristics, and lung histopathology in preterm infants with PH/HRF. Methods Retrospective chart review was conducted to determine characteristics of 93 preterm infants treated with iNO in the first 28 days and compared with 930 matched controls. Factors associated with survival with preterm HRF and smooth muscle actin from nine autopsies were evaluated. Results Preterm neonates treated with iNO had a higher incidence of preterm prolonged rupture of membrane (pPROM ≥ 18 hours), oligohydramnios and delivered by C-section. In infants treated with iNO, antenatal steroids (odds ratio [OR],3.7; confidence interval [CI], 1.2-11.3; p = 0.02), pPROM (OR, 1.001; CI, 1.0-1.004; p = 0.3), and oxygenation response to iNO (OR, 3.7; CI, 1.08-13.1; p = 0.037) were associated with survival. Thirteen infants with all three characteristics had 100% (13/13) survival without severe intraventricular hemorrhage (IVH)/periventricular leukomalacia (PVL) compared with 48% survival (12/25, p = 0.004) and 16% severe IVH/PVL without any of these factors. Severity of HRF correlated with increased smooth muscle in pulmonary vasculature. Conclusion Preterm infants with HRF exposed to antenatal steroids and pPROM had improved oxygenation with iNO and survival without severe IVH/PVL. Precisely targeting this subset may be beneficial in future trials of iNO.

Evaluation of Timing and Route of Epinephrine in a Neonatal Model of Asphyxial Arrest

Background

Epinephrine administered by low umbilical venous catheter (UVC) or endotracheal tube (ETT) is indicated in neonates who fail to respond to positive pressure ventilation and chest compressions at birth. Pharmacokinetics of ETT epinephrine via fluid‐filled lungs or UVC epinephrine in the presence of fetal shunts is unknown. We hypothesized that epinephrine administered by ETT or low UVC results in plasma epinephrine concentrations and rates of return of spontaneous circulation (ROSC) similar to right atrial (RA) epinephrine.

Methods and Results

Forty‐four lambs were randomized into the following groups: RA epinephrine (0.03 mg/kg), low UVC epinephrine (0.03 mg/kg), postcompression ETT epinephrine (0.1 mg/kg), and precompression ETT epinephrine (0.1 mg/kg). Asystole was induced by umbilical cord occlusion. Resuscitation was initiated following 5 minutes of asystole. Thirty‐eight of 44 lambs achieved ROSC (10/11, 9/11, and 12/22 in the RA, UVC, and ETT groups, respectively; subsequent RA epinephrine resulted in a total ROSC of 19/22 in the ETT groups). Median time (interquartile range) to achieve ROSC was significantly longer in the ETT group (including those that received RA epinephrine) compared to the intravenous group (4.5 [2.9–7.4] versus 2 [1.9–3] minutes; P=0.02). RA and low UVC epinephrine administration achieved comparable peak plasma epinephrine concentrations (470±250 versus 450±190 ng/mL) by 1 minute compared to ETT values of 130±60 ng/mL at 5 minutes; P=0.03. Following ROSC with ETT epinephrine alone, there was a delayed peak epinephrine concentration (652±240 ng/mL).

Conclusions

The absorption of ETT epinephrine is low and delayed at birth. RA and low UVC epinephrine rapidly achieve high plasma concentrations resulting in ROSC.

Oral Dextrose Gel Reduces the Need for Intravenous Dextrose Therapy in Neonatal Hypoglycemia

BACKGROUND

Newborn infants with risk factors may require intravenous (IV) dextrose for asymptomatic hypoglycemia. Administration of IV dextrose and transfer to the neonatal intensive care unit (NICU) may interfere with parent-infant bonding.

OBJECTIVE

To study the effect of implementing dextrose gel supplement with feeds in late preterm/term infants affected by asymptomatic hypoglycemia on reducing IV dextrose therapy.

METHOD

A retrospective study was conducted before and after dextrose gel use: 05/01/2014 to 10/31/2014 and 11/01/2014 to 04/30/2015, respectively. Asymptomatic hypoglycemic (blood glucose level <45 mg/dl) infants in the newborn nursery (NBN) were given a maximum of 3 doses of dextrose gel (200 mg/kg of 40% dextrose) along with feeds. Transfer to the NICU for IV dextrose was considered treatment failure.

RESULTS

Dextrose gel with feeds increased the blood glucose level in 184/250 (74%) of asymptomatic hypoglycemic infants compared to 144/248 (58%) with feeds only (p < 0.01). Transfer from the NBN to the NICU for IV dextrose decreased from 35/1,000 to 25/1,000 live births (p < 0.01). Exclusive breastfeeding improved from 19 to 28% (p = 0.03).

CONCLUSIONS

Use of dextrose gel with feeds reduced the need for IV fluids, avoided separation from the mother and promoted breastfeeding. Neonates who failed dextrose gel therapy were more likely to be large for gestational age, delivered by cesarean section and had lower baseline blood glucose levels.

Neonatal resuscitation adhering to oxygen saturation guidelines in asphyxiated lambs with meconium aspiration

BACKGROUND

The Neonatal Resuscitation Program (NRP) recommends upper and lower limits of preductal saturations (SpO2) extrapolated from studies in infants resuscitated in room air. These limits have not been validated in asphyxia and lung disease.

METHODS

Seven control term lambs delivered by cesarean section were ventilated with 21% O2. Thirty lambs with asphyxia with meconium aspiration were randomly assigned to resuscitation with 21% O2 (n = 6), 100% O2 (n = 6), or initiation with 21% O2 followed by variable FIO2 to maintain NRP target SpO2 ranges (n = 18). Hemodynamic and ventilation parameters were recorded for 15 min.

RESULTS

Control lambs maintained preductal SpO2 near the lower limit of NRP target range. Asphyxiated lambs had low SpO2 (38 ± 2%), low arterial pH (6.99 ± 0.01), and high PaCO2 (96 ± 7 mm Hg) at birth. Resuscitation with 21% O2 resulted in SpO2 values below the target range with low pulmonary blood flow (Qp) compared to variable FIO2 group. The increase in PaO2 and Qp with variable FIO2 resuscitation was similar to control lambs.

CONCLUSION

Maintaining SpO2 as recommended by NRP by actively adjusting inspired O2 leads to effective oxygenation and higher Qp in asphyxiated lambs with lung disease. Our findings support the current NRP SpO2 guidelines for O2 supplementation during resuscitation of an asphyxiated neonate.

Continuous End-Tidal Carbon Dioxide Monitoring during Resuscitation of Asphyxiated Term Lambs

BACKGROUND

The Neonatal Resuscitation Program (NRP) recommends close monitoring of oxygenation during the resuscitation of newborns using a pulse oximeter. However, there are no guidelines for monitoring carbon dioxide (CO2) to assess ventilation. Considering that cerebral blood flow (CBF) correlates directly with PaCO2, continuous capnography monitoring of end-tidal CO2 (ETCO2) may limit fluctuations in PaCO2 and, therefore, CBF during resuscitation of asphyxiated infants.

OBJECTIVE

To evaluate whether continuous monitoring of ETCO2 with capnography during resuscitation of asphyxiated term lambs with meconium aspiration will prevent fluctuations in PaCO2 and carotid arterial blood flow (CABF).

METHODS

Fifty-four asphyxiated term lambs with meconium aspiration syndrome were mechanically ventilated from birth to 60 min of age. Ventilatory parameters were adjusted based on clinical observation (chest excursion) and frequent arterial blood gas analysis in 24 lambs (control group) and 30 lambs (capnography group) received additional continuous ETCO2 monitoring. Left CABF was monitored. We aimed to maintain PaCO2 between 35 and 50 mm Hg and ETCO2 between 30 and 45 mm Hg.

RESULTS

There was a significant correlation between ETCO2 and PaCO2 (R = 0.7, p < 0.001), between PaCO2 and carotid flow (R = 0.52, p < 0.001) and between ETCO2 and carotid flow (R = 0.5, p < 0.001). PaCO2 and CABF during the first 60 min of age showed significantly higher fluctuation in the control group compared to the capnography group.

CONCLUSION

Continuous monitoring of ETCO2 using capnography with mechanical ventilation during and after resuscitation in asphyxiated term lambs with meconium aspiration limits fluctuations in PaCO2 and CABF and may potentially limit brain injury.

Tracheal suctioning improves gas exchange but not hemodynamics in asphyxiated lambs with meconium aspiration

BACKGROUND

Current neonatal resuscitation guidelines recommend tracheal suctioning of nonvigorous neonates born through meconium-stained amniotic fluid.

METHODS

We evaluated the effect of tracheal suctioning at birth in 29 lambs with asphyxia induced by cord occlusion and meconium aspiration during gasping.

RESULTS

Tracheal suctioning at birth (n = 15) decreased amount of meconium in distal airways (53 ± 29 particles/mm(2) lung area) compared to no suction (499 ± 109 particles/mm(2); n = 14; P < 0.001). Three lambs in the suction group had cardiac arrest during suctioning, requiring chest compressions and epinephrine. Onset of ventilation was delayed in the suction group (146 ± 11 vs. 47 ± 3 s in no-suction group; P = 0.005). There was no difference in pulmonary blood flow, carotid blood flow, and pulmonary or systemic blood pressure between the two groups. Left atrial pressure was significantly higher in the suction group. Tracheal suctioning resulted in higher Pao2/FiO2 levels (122 ± 21 vs. 78 ± 10 mm Hg) and ventilator efficiency index (0.3 ± 0.05 vs.0.16 ± 0.03). Two lambs in the no-suction group required inhaled nitric oxide. Lung 3-nitrotyrosine levels were higher in the suction group (0.65 ± 0.03 ng/µg protein) compared with the no-suction group (0.47 ± 0.06).

CONCLUSION

Tracheal suctioning improves oxygenation and ventilation. Suctioning does not improve pulmonary/systemic hemodynamics or oxidative stress in an ovine model of acute meconium aspiration with asphyxia.

Oxygen saturation index and severity of hypoxic respiratory failure

BACKGROUND

The oxygenation index (OI = mean airway pressure, MAP × FiO2 × 100 : PaO2) is used to assess the severity of hypoxic respiratory failure (HRF) and persistent pulmonary hypertension of the newborn (PPHN). An indwelling arterial line or arterial punctures are necessary to obtain PaO2 for the calculation of OI. Oxygenation can be continuously and noninvasively assessed using pulse oximetry. The use of the oxygen saturation index (OSI = MAP × FiO2 × 100 : SpO2) can be an alternate method of assessing the severity of HRF.

OBJECTIVE

To evaluate the correlation between OSI and OI in the following: (1) neonates with HRF and (2) a lamb model of meconium aspiration syndrome.

METHODS

Human neonates: a retrospective chart review of 74 ventilated late preterm/term neonates with indwelling arterial access and SpO2 values in the first 24 h of life was conducted. OSI and OI were calculated and correlated. Lamb model: arterial blood gases were drawn and preductal SpO2 was documented in 40 term newborn lambs with asphyxia and meconium aspiration. OI and OSI were calculated and correlated with pulmonary vascular resistance (PVR).

RESULTS

Mean values of OSI and OI showed a correlation coefficient of 0.952 in neonates (mean value of 308 observations in 74 neonates) and 0.948 in lambs (mean value of 743 observations in 40 lambs). In lambs, with increasing PVR, there was a decrease in OI and OSI.

CONCLUSION

OSI correlates significantly with OI in infants with HRF. This noninvasive measure may be used to assess the severity of HRF and PPHN in neonates without arterial access.

L(9) orthogonal design assisted formulation and evaluation of chitosan-based buccoadhesive films of miconazole nitrate

The present study was aimed to prepare and evaluate buccoadhesive films of miconazole nitrate (MCZ). The films based on chitosan were prepared by solvent casting method using L(9) orthogonal array design to release the drug above its minimum inhibitory concentration (MIC) for a prolonged period of time so as to reduce its frequency of administration. As per the experimental design, guar gum, HPMC K15M and HEC were added at three different levels to control the drug release. Films showed smooth, uniform and non-sticky surface with good flexibility and folding endurance. Thickness and weight-variation data showed no significant difference among the batches, indicating that the polymeric blend possessed a good film forming ability and its desired properties could easily be achieved by varying the composition of the casting solution. Films composed of chitosan with guar gum appeared to be tougher; comparatively more bioadhesive in vitro, resided to an appropriate time interval and swelled at a more reasonable rate than those containing HPMC and HEC, suggesting the superiority of guar gum over other polymers. In vitro drug release studies conducted on all batches and microbiological studies done on the statistically optimized formulation demonstrated that the films had ability to sustain the drug concentration above its MIC for 6 hrs, despite the incorporation of a smaller dose (2.5 mg/cm(2) of the film). Films, except CF2 and CF3, followed Fickian diffusion of release mechanism. FT-IR spectra revealed no interactions between the drug and polymers.

Enhanced transdermal delivery of ketoprofen from bioadhesive gels

The aim of this study was to evaluate and compare the in vitro and in vivo transdermal potential of bioadhesive gels of ketoprofen by using gelling polymers like sodium carboxymethylcellulose, xanthan gum, poloxamer 407 and carbopol 934P as bioadhesive polymer with and without penetration enhancer (oleic acid). The effect of oleic acid as a penetration enhancer was examined when it was added to the bioadhesive formulations. Gels were evaluated for bioadhesive force and viscosity. To study the in vitro potential of these formulations, permeation studies were performed with Franz diffusion cell using excised rat abdominal skin. Carrageenan induced rat paw edema model was used to investigate their in vivo performance. The commercial formulation of ketoprofen was used as a reference formulation. The in vitro permeation studies indicate that ketoprofen bioadhesive gel of poloxamer 407 with penetration enhancer was superior to gels of sodium carboxymethylcellulose and xanthan gum with penetration enhancer (oleic acid). The permeation rate of ketoprofen from poloxamer 407 based bioadhesive gel with 15% v/w penetration enhancer was higher (rat abdominal skin flux = 0.421 +/- 0.032 mg/cm(2)/h) than the permeation rate of sodium carboxymethylcellulose and xanthan gum based bioadhesive gel with 15% v/w penetration enhancer. In the paw edema test poloxamer 407 based bioadhesive gel with 15% v/w penetration enhancer showed the best permeation and effectiveness. The in vitro and in vivo studies showed that bioadhesive gels of ketoprofen could be used for effective therapy.

Pegylated protein encapsulated multivesicular liposomes: a novel approach for sustained release of interferon alpha

Hepatitis C viral chemotherapy suffers from a relatively short half-life of the interferon alpha-2a (IFN alpha). To address this issue, we investigated the effects of polyethylene glycol modification and their subsequent encapsulation in multivesicular liposomes (MVLs), on the release properties of IFN alpha. In the present study, interferon-alpha was conjugated with methoxy-polyethylene glycol (mPEG, MW 5000). Prepared IFN alpha-mPEG5000 conjugate (IFN alpha-mPEG5000) was purified with size exclusion chromatography. The relative in vitro anti-viral activity of pegylated interferon alpha-2a was found to 87.9% of the unmodified IFN alpha. Pegylated IFN alpha encapsulated multivesicular liposomes were prepared by double emulsification technique followed by evaporation of organic solvents from chloroform ether spherules suspended in water. Prepared MVLs were then characterized for shape, size, vesicle count, encapsulation efficiency, and in vitro release rate. In process stability studies of pegylated IFN alpha protein exhibited better stability when exposed to chloroform: diethyl ether (1:1 ratio) mixture as well as variable vortexing time as compared to native IFN alpha. Relatively high percentage of encapsulation of protein ( approximately 75%) was achieved. In vitro release profile of pegylated IFN alpha-mPEG5000 containing MVLs in the PBS showed lower initial burst release with sustained and incomplete release over a period of 1 week. In contrast, native IFN alpha entrapped MVLs were observed as higher initial burst release, i.e., nearly 35% followed by almost complete release. The results confirmed the possibility of multivesicular liposomes as a long-acting or sustained-release delivery system using a combination of pegylation and encapsulation technique for controlled delivery of interferon alpha.

Distribution and partitioning of phosphorus in solid waste and sediments from drainage canals in the industrial belt of Delhi, India

Phosphorus is an essential and often limiting nutrient in both marine and freshwater ecosystems. However, its oversupply is of great concern in many environments due to its role in eutrophication. The concentration and distribution of sediment bound phosphorus species not only record its input into the environment, but also suggest their possible sources. It is recognized that the features of phosphorus behaviour have not been extensively studied in urban environments. In this study, phosphorus in solid waste and sediments from drainage canals within the industrial belt of Delhi were fractionated into five operationally defined forms, i.e., exchangeable or loosely sorbed phosphorus (Exch-P), Fe-bound phosphorus (Fe-P), authigenic apatite, CaCO3-bound phosphorus and biogenic apatite (Acet-P), detrital apatite (Det-P) and organic-bound phosphorus (Org-P), in order to assess the potential bioavailability status in these systems.

Distribution and fractionation of heavy metals in solid waste from selected sites in the industrial belt of Delhi, India

Solid waste samples were collected from five small-scale industrial sites in the National Capital Territory (NCT) of Delhi. These industrial sites represent the regional spread of the industrial belt in the NCT of Delhi. Solid waste samples were digested using aqua-regia and HF in air tight teflon bombs for the quantitative analysis of heavy metals (Hg, Pb, Cd, Mn, Fe, Ni, Cu and Zn) by GBC model 902 atomic absorption spectrophotometer. Hg was analysed using hydrid generator attachment. Beside this sequential extraction was used to fractionate five heavy metals (Pb, Ni, Cd, Cu and Zn) into six operationally defined phases, viz. water soluble, exchangeable, carbonate-bound, Fe-Mn oxides, organic-bound and residual fractions to ascertain the relative mobility of these metals. The result obtained showed metal concentration to be in the range of Hg 0.42-2.3; Pb 23-530; Cd 014-224; Mn 494-19 964; Fe 35 684-233 119; Ni 192-1534; Cu 3065-10 144 and Zn 116-23 321 (all units in mg kg(-1)) in all the industrial areas studied. The fractionated toxic metals like Pb, Ni and Cd were observed to be in the range of 25-35, 15-50 and 40-50%, respectively, in mobile or bio-available fractions of solid waste. As this waste is often disposed-off by the roadsides, low lying areas, abandoned quarries or in landfill sites which are often not properly planned, thus posing potential risk to ground and surface water quality to millions of people living downstream.

The Regulation of Carbonic Anhydrase and Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Activase by Light and CO2 in Chlamydomonas reinhardtii

We have investigated the regulation of accumulation of ribulose-1,5-bisphosphate carboxylase/oxygenase activase and the periplasmic carbonic anhydrase (CA) in Chlamydomonas reinhardtii. In algae, the periplasmic CA is required for efficient CO2 fixation when the CO2 concentration is low. These two proteins are affected differently by the CO2 level in the environment. The steady-state level of the ribulose-1,5-bisphosphate carboxylase/oxygenase activase transcript was only slightly and transiently affected by a reduction in ambient CO2 concentration, whereas the CA transcript level was strongly induced by air containing ambient (350 parts per million) CO2 (low CO2) conditions. The transcripts for both proteins showed strong oscillations when the alga was grown under a 12-h light/12-h dark growth regime, with the transcripts encoding these proteins present just before the onset of the light cycle. The observation that the CA transcript was made in the dark was surprising, since earlier reports indicated that active photosynthesis was required for the induction of the periplasmic CA. Further experiments demonstrated that the CA transcript was partially induced under low-CO2 conditions even when the switch to low CO2 was done in the dark. Our results suggest that C. reinhardtii might sense the CO2 concentration in a more direct manner than through C2 or C3 cycle intermediates, which has been previously suggested.

Characterization of lamprin, an unusual matrix protein from lamprey cartilage. Implications for evolution, structure, and assembly of elastin and other fibrillar proteins

Lamprin, an insoluble non-collagen, non-elastin protein, is the major connective tissue component of the fibrillar extracellular matrix of lamprey annular cartilage. Here we demonstrate that the soluble monomer of lamprin is a family of highly hydrophobic, self-aggregating proteins with molecular masses of 12 and 10 kDa. Two mRNAs for soluble lamprin were identified (0.9 and 2 kilobases), differing principally in the length of their 3'-untranslated tails. Variants of soluble lamprin appear to arise both as the products of multiple genes and by alternate splicing. Although not generally homologous to any other protein, soluble lamprins contain a tandemly repeated peptide sequence (GGLGY) which is present in both silkmoth chorion proteins and spider dragline silk. Strong homologies to this repeat sequence are also present in several mammalian and avian elastins. Monoclonal antibodies to VGVAPG, a repeated sequence in human elastin, also cross-react with lamprin. We suggest that these proteins share a structural motif which promotes self-aggregation and fibril formation in proteins through interdigitation of hydrophobic side chains in beta-sheet/beta-turn structures, a motif that has been preserved in recognizable form over several hundred million years of evolution.

Hyperfractionation in advanced head and neck cancer

This preliminary study was undertaken to observe tumour response and normal tissue tolerance to hyperfractionation. This study showed encouraging locoregional control rate in advanced head and neck cancer. Responses T4 tumors are poor and are prone to recur. This indicates that probably greater dose is needed to control T4 disease. We used 7920 cGy for T4 and late T3 status tumour. This dose is well tolerated by patients. Control of T4 tumours may further be increased by increasing total dose, but in view of inadequate clear cut numerical data of tissue tolerance derived by L-Q = Linear Quadratic formula which is still under clinical trial, further increase in total dose cannot be overemphasized. Longer follow up is necessary to assess the long term control rate and late tissue reaction. There is a need of randomized controlled clinical trial to compare hyperfractionation and conventional fractionation. In next phase we are undertaking randomized study of twice daily, daily and weekly fractionation in advanced head and neck cancer.

Partial characterization of a new isoenzyme of carbonic anhydrase isolated from Chlamydomonas reinhardtii

A new isoenzyme of carbonic anhydrase has been isolated and purified from Chlamydomonas reinhardtii. This carbonic anhydrase is composed of two nonidentical subunits with apparent molecular masses of 39 and 4.5 kDa and is located in the periplasmic space. This is the second periplasmic carbonic anhydrase found in C. reinhardtii. Two genes, CAH1 and CAH2, which code for carbonic anhydrase, have been recently described by Fujiwara et al. (Fujiwara, S., Fukuzawa, H., Tachiki, A., and Miyachi, S. (1990) Proc. Natl. Acad, Sci. U.S.A. 87, 9779-9783). The CAH1 gene codes for a periplasmic carbonic anhydrase which is induced under low CO2 conditions and is well characterized. The carbonic anhydrase characterized in this report was isolated from a mutant that is unable to synthesize the CAH1 gene product. Amino acid sequencing demonstrates that this newly isolated carbonic anhydrase is the CAH2 gene product. This is the first report of another functional carbonic anhydrase in C. reinhardtii.