Bridging disciplines to advance elasmobranch conservation: applications of physiological ecology.

A strength of physiological ecology is its incorporation of aspects of both species' ecology and physiology; this holistic approach is needed to address current and future anthropogenic stressors affecting elasmobranch fishes that range from overexploitation to the effects of climate change. For example, physiology is one of several key determinants of an organism's ecological niche (along with evolutionary constraints and ecological interactions). The fundamental role of physiology in niche determination led to the development of the field of physiological ecology. This approach considers physiological mechanisms in the context of the environment to understand mechanistic variations that beget ecological trends. Physiological ecology, as an integrative discipline, has recently experienced a resurgence with respect to conservation applications, largely in conjunction with technological advances that extended physiological work from the lab into the natural world. This is of critical importance for species such as elasmobranchs (sharks, skates and rays), which are an especially understudied and threatened group of vertebrates. In 2017, at the American Elasmobranch Society meeting in Austin, Texas, the symposium entitled `Applications of Physiological Ecology in Elasmobranch Research' provided a platform for researchers to showcase work in which ecological questions were examined through a physiological lens. Here, we highlight the research presented at this symposium, which emphasized the strength of linking physiological tools with ecological questions. We also demonstrate the applicability of using physiological ecology research as a method to approach conservation issues, and advocate for a more available framework whereby results are more easily accessible for their implementation into management practices.

A review of the anatomy of the upper airway in early infancy and its possible relevance to SIDS.

BACKGROUND: Since the danger of prone sleeping in the first 6 months of life has been publicised, there has been a dramatic and consistent reduction in the incidence of sudden infant death syndrome (SIDS). However, unexpected infant deaths and apparent life-threatening events (ALTEs) continue to occur that are clearly not associated with known epidemiological risk factors. AIMS: To review the unique features of the anatomy and function of the upper airway of the young infant which contribute to increased vulnerability to hypoxia in this age group. We discuss the clinical identification of those infants at risk of obstruction or restriction of the upper airway and the management of the 'at risk' infant. CONCLUSIONS: In the era after the "back to sleep" campaigns, it is likely that an increasing proportion of cases of ALTEs and SIDS will be related to obstruction or limitation of upper airway size leading to sleep hypoxia/asphyxia. This type of problem may be anticipated by evaluation and investigation of infants with signs or a clinical history consistent with possible upper respiratory tract compromise, including micrognathia.

Neurodevelopmental outcome of infants treated with head cooling and mild hypothermia after perinatal asphyxia.

OBJECTIVES: To determine the neurodevelopmental outcome of infants treated with head cooling with systemic hypothermia after hypoxic-ischemic encephalopathy. STUDY DESIGN: Infants >/=37 weeks' gestation, who had an umbilical artery pH

Delayed hypotension and subendocardial injury after repeated umbilical cord occlusion in near-term fetal lambs.

OBJECTIVE: This study was undertaken to determine whether myocardial injury occurs after repeated intrauterine asphyxia. STUDY DESIGN: Near-term fetal sheep with implanted instrumentation underwent either sham occlusions (n = 8) or repeated brief umbilical cord occlusions (n = 12) continued until the onset of severe (<20 mm Hg) or sustained hypotension. After 3 days of recovery, the fetal hearts were perfusion fixed. RESULTS: Repeated umbilical cord occlusions led to a severe metabolic acidosis (pH, 6.84 +/- 0.09; lactate concentration, 14.1 +/- 1.5 mmol/L) with increasing hypotension during occlusions, which were terminated after 128 +/- 38 minutes. After the occlusions, the mean arterial pressure showed a delayed fall, which resolved after 12 hours. Ultrastructural examination showed evidence of subendocardial injury, with dilatation of sarcoplasmic reticulum, margination and clumping of nuclear chromatin, and mitochondrial swelling. The most severe morphologic changes, including electron-dense mitochondrial inclusions, were found in the fetuses with delayed recovery of the fetal heart rate after the final occlusion. CONCLUSION: Subendocardial injury occurs after severe repeated intrauterine asphyxia in the late-gestation fetus, and this may contribute to cardiovascular compromise and the development of late decelerations.

Does early hospital discharge with home support of families with preterm infants affect breastfeeding success? A randomized trial.

UNLABELLED: The aim of the present study was to determine if earlier discharge of preterm infants (<37 wk) from hospital is safe and if it affects breastfeeding rates. In a pilot observational study, premature infants received full oral (sucking) feeds for a mean (SD) 7.7 +/- 7.9 d before discharge. In the main study, 308 preterm infants were randomly assigned to either Early Discharge (148 infants) when fully orally fed but not yet gaining weight or Routine Discharge (160 infants) when fully orally fed and also gaining weight before discharge. A further 122 mothers declined randomization. The Early Discharge group was followed by Visiting Nurse Specialists who were available 24 h a day, while the Routine group was followed by the Home Care Nurses available on week days. There were no significant differences between the groups in birthweight or gestational age. The Early Discharge group were discharged 2.5 +/- 2 d after full oral feeding compared to 4.4 +/- 2.7 d for the Routine group (p < 0.001) and 6.1 +/- 5 d for those who declined. However, there was no significant difference between the Early and Routine groups for breastfeeding either at discharge (80 vs 83%), or 6 wk (55 vs 60%) or 6 mo after discharge (36 vs 36%), or for weight gain, or rates of re-hospitalization (8.8% vs 11.9% at 6 wk, p = 0.37). CONCLUSION: Early discharge from hospital once a preterm infant can take full oral feeds does not alter later breastfeeding rates when adequate visiting nursing support is available.

Pregnancy outcome in women with reflux nephropathy and the inheritance of vesico-ureteric reflux.

In women with reflux nephropathy, we investigated whether pre-existing hypertension and impaired renal function influence the rates of preeclampsia, renal function deterioration and preterm birth. The infants were investigated for vesico-ureteric reflux (VUR). A prospective audit of 54 pregnancies in 46 women with reflux nephropathy was performed. Preeclampsia complicated 24% of pregnancies and was increased in women with pre-existing hypertension (42%) compared with normotensive women (14%), (RR 3.0 (95% CI 1.1-7.8)). Nine (18%) women experienced deterioration in renal function during pregnancy Women with mild or moderate renal impairment were at increased risk of renal function deterioration (RR 12.7 (95% CI 1.6-98.5); RR 19.8 (95% CI 2.6-155)), respectively A third of infants were delivered preterm. The risk of preterm birth was increased if the mother had pre-existing hypertension (p = 0.01) or moderate renal impairment (p = 0.002). Seventeen (43%) of the 40 infants who underwent micturating cystourethrography had VUR, consistent with autosomal dominant inheritance with reduced penetrance. In reflux nephropathy, pre-existing hypertension was associated with an increased risk of preeclampsia and pre-existing renal impairment with deterioration in renal function. Infants of women with reflux nephropathy should be screened for VUR.

Neonatal micrognathia is associated with small upper airways on radiographic measurement.

In order to determine if infants with clinical micrognathia identified in the newborn period have smaller upper airways than do normal infants, and if their airway size is related to risk of later apnoea, respiration-timed upper airway radiographic measurements were performed in 21 asymptomatic neonates with clinical micrognathia. Their radiographic measurements were compared with those of a previously reported cohort of 35 normal infants. The micrognathic infants and a control group of 27 infants referred for parental anxiety were followed for 6 mo on home apnoea monitors. Sleep apnoea at home requiring stimulation by the parents occurred in 6 of 7 infants with micrognathia associated with craniofacial anomalies, 9 of 14 (64%) infants with isolated micrognathia, but only 1 of the 27 control infants (p < 0.001). Upper airway measurements at term of the infants with isolated micrognathia who later experienced apnoea were significantly smaller than either those of normal infants (p < 0.01) or of micrognathic infants who did not have apnoea requiring stimulation (p < 0.05). In conclusion, upper airway measurements on timed lateral radiographs in asymptomatic micrognathic infants at term (corrected age) revealed them to be smaller than those of normal infants. Narrower upper airways were associated with increased risk of subsequent apnoea requiring stimulation.

Is changing the sleep environment enough? Current recommendations for SIDS.

Sudden infant death syndrome (SIDS or cot death) was the major cause of post-neonatal infant death in many countries in the late 1970s and 1980s. There is now very strong evidence that public intervention campaigns targeting the prone sleeping position, which had been identified by epidemiological studies as a major risk factor, were followed by substantial falls in the rate of SIDS. In the present review we discuss the evidence on which current recommendations for the prevention of SIDS are based. The prone sleeping position is now clearly causally associated with SIDS. Further reductions in SIDS may be produced by recommending the back sleeping position as opposed to the side position. Maternal smoking in pregnancy and bed sharing by infants of mothers who smoke are also strongly associated with SIDS, but have been harder to influence. Paternal smoking has also been implicated, although the magnitude of the reported risk is small. Finally, breastfeeding, pacifier use and having the infant sharing the parents bedroom, but not the bed, may also reduce risk. Continued reductions in SIDS mortality will require innovative public health education to target these major risk factors, while building on the "back to sleep" approach.

Cerebral hypothermia is not neuroprotective when started after postischemic seizures in fetal sheep.

Prolonged cerebral hypothermia is neuroprotective if started within a few hours of hypoxia-ischemia. However, delayed seizure activity is one of the major clinical indicators of an adverse prognosis after perinatal asphyxia. The aim of this study was to determine whether head cooling delayed until after the onset of postasphyxial seizures may still be neuroprotective. Unanesthetized near-term fetal sheep in utero received 30 min of cerebral ischemia induced by bilateral carotid artery occlusion. Eight and one-half hours later, they received either cooling (n = 5) or sham cooling (n = 13) until 72 h after the insult. Intrauterine cooling, induced by circulating cold water through a coil around the fetal head, was titrated to reduce fetal extradural temperature from 39.4+/-0.1 degrees C to between 30 and 33 degrees C. Cerebral ischemia led to the delayed development of intense epileptiform activity from 6 to 8 h postinsult, followed by a marked secondary rise in cortical impedance (a measure of cytotoxic edema) and in carotid blood flow. Cerebral cooling markedly attenuated the secondary rise in impedance and reduced carotid blood flow (p < 0.001). After 5 d recovery, there was no significant difference in loss of parietal EEG activity relative to baseline in the hypothermia compared with the control group (-12.5+/-1.4 versus -15.2+/-1.2 dB, mean +/- SEM, NS) or in parasagittal cortical neuronal loss (82+/-9 versus 90+/-5%, NS). In conclusion, delayed prolonged head cooling begun after the onset of postischemic seizures was not neuroprotective. These data highlight the importance of intervention in the latent phase, after reperfusion but before the onset of secondary injury.

Antecedents of neonatal encephalopathy with fetal acidaemia at term.

OBJECTIVE: To identify the relative contribution of antenatal hypoxia, obstetric catastrophe during labour and fetal monitoring practice to the occurrence of neonatal encephalopathy associated with acidaemia at term. DESIGN: Prospective study. SETTING: Tertiary referral hospital in Auckland, New Zealand. SAMPLE: Twenty-two term babies born between January 1996 and October 1997 with umbilical artery pH < or = 7.09 (median 6.88) or 5 minute Apgar score < 7 (median 5.0), and moderate to severe encephalopathy within five hours of birth. METHODS: Antenatal and intrapartum events and fetal heart rate monitoring practice were reviewed by an experienced obstetrician. RESULTS: More than half the cases were associated with events beyond the control of the clinician: 5 of 22 (23%) had evidence of antenatal hypoxia and 5 of 22 (23%) experienced an obstetric catastrophe during labour. Use of continuous fetal monitoring techniques or the interpretation of fetal heart rate changes was suboptimal in 8 of 12 cases. Continuous monitoring was not performed at all in three cases. All pregnancies were of either low or medium risk; none had proteinuric hypertension and no case was breech, small for gestational age or had a gestational age > or = 42 weeks. CONCLUSIONS: A significant proportion of babies with encephalopathy associated with acidaemia at term experienced either antenatal hypoxia or catastrophic events beyond the control of the clinician. Further improvements in obstetric care will require greater vigilance in low to medium risk pregnancies and improved fetal monitoring practice during both induction and labour.

Caffeine overdose in a premature infant: clinical course and pharmacokinetics.

The elimination of caffeine was investigated in a 1860 g, 31 week gestation neonate, following the accidental administration of a 160 mg.kg-1 dose. The first serum concentration measured was 217.5 mg.l-1 at 36.5 h after dosing. Fitting of time-concentration data was performed using non-linear regression with MKMODEL. A first order elimination model was superior to a mixed order model. Parameter estimates were: clearance 0.01 l.h-1, volume of distribution 1.17 litres, elimination half-life 81 h. Toxic manifestations included hypertonia, sweating, tachycardia, cardiac failure, pulmonary oedema and metabolic disturbances (metabolic acidosis, hyperglycaemia and creatine kinase elevation). An unusual feature of this infant's illness course was gastric dilatation. These signs resolved by day 7 at a serum concentration of 60-70 mg.l-1. Caffeine clearance has traditionally been reported as either an absolute value or as directly proportional to body weight. The per kilogram model gives an erroneous impression that clearance is greatest in early childhood and then decreases with age until adult rates are reached in late adolescence. Age-related clearance values reported in the literature were reviewed using an allometric 3/4 power model. This size model demonstrates that clearance increases in infancy and reaches adult rates within the first three months of life.

Is urethral catheterization a successful alternative to suprapubic aspiration in neonates?

OBJECTIVE: To compare urine collection by urethral catheterization with suprapubic aspiration in a neonatal intensive care unit. METHODOLOGY: All urine collections were documented, the collection methods attempted recorded and success rates calculated. The incidence of contaminated specimens was determined. The infants ranged in weight from 570 g to 4180 g and in gestation from 24 to 44 weeks. RESULTS: Thirty-two out of 65 (49%) suprapubic aspirations were successful. Overall 33/42 (77%) of catheterizations were successful, 12/18 (67%) were successful when following an unsuccessful SPA. No SPA was contaminated compared to 7/22 (22%) of the catheter specimens. Urinary tract infection was present in 4/63 (6.3%) infants. There were no complications following catheterization. CONCLUSIONS: Urethral catheterization is a useful and safe alternative to suprapubic aspiration, but suprapubic aspiration remains the method of first choice.

The successful containment of coxsackie B4 infection in a neonatal unit.

This report describes the containment of a potential enterovirus epidemic in a neonatal intensive care unit. A case of neonatal enterovirus meningitis and myocarditis was identified. Polymerase chain reaction (PCR) was used to assist in appropriate cohorting of contacts. One further infant became cross-infected with Coxsackie B4. Serum PCR was accurate in detecting the infection in the early stages in this asymptomatic neonate. Neonatal enterovirus infection is relatively rare but has the potential to cause outbreaks in neonatal wards. PCR can be used to diagnose and monitor for cross infection.

Neuroprotection with prolonged head cooling started before postischemic seizures in fetal sheep.

OBJECTIVE: Cerebral hypothermia has been shown to reduce damage from experimental hy-poxia-ischemia if started shortly after reperfusion. However, in the newborn infant it may not be feasible to determine prognosis so soon after exposure to asphyxia. The aim of this study was to determine whether head cooling, delayed until shortly before the onset of postasphyxial seizure activity, is neuroprotective. METHODS: Unanesthetized near-term fetal sheep in utero were subjected to 30 minutes of cerebral ischemia. Later, at 5.5 hours, they were randomized to either cooling (n = 7) or sham cooling (n = 10) for 72 hours. Intrauterine cooling was induced by circulating cold water through a coil around the fetal head. The water temperature was titrated to reduce fetal extradural temperature from 39.1 +/- 0.1 degreesC to between 30 degreesC and 33 degreesC, while maintaining esophageal temperature >37 degreesC. RESULTS: Cerebral cooling suppressed the secondary rise in cortical impedance (a measure of cytotoxic edema), but did not prevent delayed seizures, 8 to 30 hours after ischemia. Transient metabolic changes including increased plasma lactate and glucose levels were seen with a moderate sustained rise in blood pressure. This severe cerebral insult resulted in depressed residual parietal electroencephalographic activity after 5 days recovery (-14.2 +/- 1.5 decibels), associated with a watershed distribution of neuronal loss (eg, 94 +/- 4% in parasagittal cortex and 77 +/- 4% in the lateral cortex). Hypothermia was associated with better recovery of electroencephalographic activity (-8.9% +/- 1.8 decibels) and substantially reduced neuronal loss in the parasagittal cortex (46 +/- 13%), the lateral cortex (9 +/- 4%), and other regions except the cornu ammonis sectors 1 and 2 of the hippocampus. CONCLUSIONS: Delayed selective head cooling begun before the onset of postischemic seizures and continued for 3 days may have potential to significantly improve the outcome of moderate to severe hypoxic-ischemic encephalopathy.

Selective head cooling in newborn infants after perinatal asphyxia: a safety study.

AIMS: To determine the practicality and safety of head cooling with mild or minimal systemic hypothermia in term neonates with moderate to severe hypoxic-ischemic encephalopathy. METHODS: Study group infants >/=37 weeks' gestation, who had an umbilical artery pH

The 'pharmacology' of neuronal rescue with cerebral hypothermia.

The neuroprotective effects of hypothermia during cerebral ischaemia or asphyxia are well known. Although, in view of this, the possibility of a therapeutic role for hypothermia during or after resuscitation from such insults has been a long standing focus of research, early studies had limited and contradictory results. Clinically and experimentally severe perinatal asphyxial injury is associated with a latent phase after reperfusion, with initial recovery of cerebral energy metabolism but EEG suppression, followed by a secondary phase with seizures, cytotoxic edema, accumulation of cytotoxins, and cerebral energy failure from 6 to 15 h after birth. Recent studies have led to the hypothesis that changes in post-ischaemic cerebral temperature can critically modulate encephalopathic processes which are initiated during the primary phase of hypoxia-ischaemia, but which extend into the secondary phase of cerebral injury. This conceptual framework allows a better understanding of the 'pharmacological' parameters that determine effective hypothermic neuroprotection, including the timing of initiation of cooling, its duration and the depth of cooling attained. Moderate cerebral hypothermia initiated in the latent phase, between one and as late as 6 hours after reperfusion, and continued for a sufficient duration in relation to the severity of the cerebral injury, has been associated with potent, long-lasting neuroprotection in both adult and perinatal species. These encouraging results must be balanced against the adverse systemic effects of hypothermia. Randomised clinical trials are in progress to establish the safety and efficacy of prolonged cerebral hypothermia.

Can preterm twins breast feed successfully?

AIM: To compare the success of singleton and twin preterm infants in establishing and maintaining breast feeding, and to evaluate the effectiveness of current programmes to promote breast feeding. METHODS: All infants less than 37 weeks gestation discharged in one month from the special care baby unit at National Womens Hospital were studied. Data on the infants and their in hospital course was recorded from the neonatal records. The mothers were contacted by telephone 3 to 4 months after discharge, to elicit the subsequent breast feeding rates. RESULTS: Thirty of 33 preterm infants (29 to 36 weeks gestation) were breast fed at discharge from hospital: 93% of singletons, and 89% of twins. The twins were older and heavier at discharge (p < 0.004) due to their longer hospital stays (28.4 vs 16.3 days, p < 0.05). All but 2 infants progressed to exclusive breast feeding. There was a similar rate of decline in the rates of breast feeding in singletons and twins to 68% at 8-12 weeks and 49% at 12-16 weeks after birth. CONCLUSIONS: Preterm twins can breast feed as successfully as preterm singleton infants; as with sufficient assistance and encouragement, their rates of breast feeding were comparable to those of term infants. Although the resources of this hospital do not allow preterm infants to become fully breast fed before discharge, the current programme at National Womens Hospital is effective in establishing successful breast feeding in these high risk infants.

Lymphatic dysplasia in a neonate with Noonan's syndrome.

We present the case of a patient with Noonan's syndrome and massive nonimmune hydrops fetalis in whom lymphangiography was performed in the neonatal period. This demonstrated generalised lymphatic dysplasia, and we suggest a mechanism by which the lymphatic abnormalities in Noonan's syndrome may arise.

Changes in risk factors for hypoxic-ischaemic seizures in term infants.

Term infants with seizures and evidence of perinatal asphyxia were prospectively identified in 1 city and 2 time periods: 1978-1981 and 1991. Infants with multiple congenital abnormalities, hypocalcaemia or infection were excluded. Although there was little change in the overall incidence of neonatal seizures between 1978-1981 (1.9 per 1,000) and 1991 (1.78 per 1,000, N.S.) there was a marked reduction in small for dates infants with seizures: 8 of 19 infants in 1978-1981 compared to none of 16 in 1991 (p < 0.005). In contrast, infants > or = 41 weeks continued to show a markedly increased risk for asphyxia (relative risk 4.48, 95% CI: 1.7-12.3). The mechanism of this improved outcome for small for gestational age infants is unknown, but speculatively may be due to improved obstetric monitoring techniques allowing early identification of compromised infants.