It is generally assumed that population size of all wild animal species is regulated through density-dependent mechanisms, but the mechanisms responsible have been difficult to identify for elephants and large whales. We have used information on physiological reproductive mechanisms in humans in a stochastic computer simulation study to explore how known density-dependent fertility mechanisms in humans could regulate population size in a hypothetical large mammal species, assuming no deliberate interference with sexual or reproductive processes. Two physiological reproductive mechanisms in women are dependent on nutrition in utero or early life: age at menarche and post-partum amenorrhea during lactation and were included in the model. If large female mammals in general have physiological reproductive mechanisms similar to human females, strong density-dependence mechanisms will be the result, but with a substantial delay, 20 to 50 years. The model results are discussed in relation to what is known about populations of the Eastern North Pacific gray whales (Eschrichtius robustus), Antarctic minke whales (Balaenoptera bonaerensis) and elephants (Loxodonta africana) in Amboseli National Park, Kenya.

Annex A: List of Participants Annex B: Agenda Annex C: List of Documents How to cite: International Whaling Commission, 2023. Report of the Scientific Committee: Annex A-C. J. Cetacean Res. Manage. (Suppl.). 24: 191-206.

BackgroundHypothermia is neuroprotective after neonatal hypoxic-ischaemic brain injury. However, systemic cooling to hypothermic temperatures is a stressor and may reduce neuroprotection in awake pigs. We compared two experiments of global hypoxic-ischaemic injury in newborn pigs, in which one group received propofol–remifentanil and the other remained awake during post-insult hypothermia treatment.MethodsIn both studies, newborn pigs were anaesthetised using halothane during a 45-min global hypoxic-ischaemic insult induced by reducing Fio2 and graded hypotension until a low-voltage <7 μV electroencephalogram was achieved. On reoxygenation, the pigs were randomly allocated to receive 24 h of normothermia or hypothermia. In the first study (n=18) anaesthesia was discontinued and the pigs' tracheas were extubated. In the second study (n=14) anaesthesia was continued using propofol and remifentanil. Brain injury was assessed after 72 h by classical global histopathology, Purkinje cell count, and apoptotic cell counts in the hippocampus and cerebellum.ResultsGlobal injury was nearly 10-fold greater in the awake group compared with the anaesthetised group (P=0.021). Hypothermia was neuroprotective in the anaesthetised pigs but not the awake pigs. In the hippocampus, the density of cleaved caspase-3-positive cells was increased in awake compared with anaesthetised pigs in normothermia. In the cerebellum, Purkinje cell density was reduced in the awake pigs irrespective of treatment, and the number of cleaved caspase-3-positive Purkinje cells was greatly increased in hypothermic awake pigs. We detected no difference in cleaved caspase-3 in the granular cell layer or microglial reactivity across the groups.ConclusionsOur study provides novel insights into the significance of anaesthesia/sedation during hypothermia for achieving optimal neuroprotection.

A substantial decline in energy storage in the Antarctic minke whale during the 18-year Japanese JARPA research programme (austral summers 1987/88–2004/05) was reported in 2008 (Konishi et al., 2008). The statistical method used in the study was simple multiple linear regression. The results have since been thoroughly discussed by the Scientific Committee of the International Whaling Commission because of the potential importance of the findings. Some had suggested that the sampling heterogeneity in the JARPA data was so substantial that generalised linear models (GLMs) with interaction terms and random-effects terms should be explored. For the present article, five response variables related to energy storage and the variable ‘stomach content weight’ are systematically analysed using GLMs. For all five energy storage variables, the results show declines in the interval 3% to 9% over the JARPA period, all significantly different from zero at the 5% level, but no later decline. The weight of sieved stomach contents declined by 25% over the same period. The coefficients of the decline and the coefficients for most other independent variables were similar to values obtained by simple linear regression, but in some cases the standard errors were larger. The results indicate that important changes took place in the Antarctic ecosystem during the 1990s. It is hypothesised that the most important cause of the changes was the simultaneous increase in numbers of other krill feeders, especially humpback whales.

Abstract Rodent models of neonatal hypoxic–ischemic (HI) injury require a subset of animals to be immobilized for continuous temperature monitoring during the insult and subsequent treatment. Restrained animals are discarded from the analysis due to the effect of restraint on the brain injury as first demonstrated by Thoresen et al 1996. However, the effects of restraint on responses to hypothermic (HT) post‐insult therapy are not well described. We examine the effects of restraint associated with different probe placements on HI brain injury. We have conducted a meta‐analysis of 23 experiments comparing probe rats (skin n = 42, rectal n = 35) and free‐moving matched non‐probe controls (n = 80) that underwent HI injury (left common carotid artery ligation and 90 min 8% O2) at postnatal day 7 (P7), followed by 5 h of NT (37°C) or HT (32°C). On P14, brain regions were analyzed for injury (by neuropathology and area loss), microglial reactivity and brain‐derived neurotrophic factor (BDNF). HI injury was mitigated in NT skin and rectal probe rats, with greater neuroprotection among the rectal probe rats. Following HT, the skin probe rats maintained the restraint‐associated neuroprotection, while brain injury was significantly exacerbated among the rectal probe rats. Microglial reactivity strongly correlated with the acquired injury, with no detectable difference between the groups. Likewise, we observed no differences in BDNF signal intensity. Our findings suggest a biphasic neuroprotection from restraint stress, which becomes detrimental in combination with HT and the presumed discomfort from the rectal probe. This finding is useful in highlighting unforeseen effects of common experimental designs or routine clinical management.

We study the effect of hypothermia (HT) following hypoxic-ischaemic (HI) brain injury in postnatal day 7 (P7) rats. In 2015, new European Union animal transport regulations prompted a change in practice at the breeding facility, which henceforth crossfostered P3 litters to P8 older lactating dams prior to transportation. It is generally assumed that crossfostering does not significantly affect the experimental results. The aim of this study was to examine whether crossfostering affects our model consistency by modifying injury susceptibility and hypothermic neuroprotection. We analysed 219 pups from 11 experiments conducted between 2013 and 2015: 73 non-crossfostered and 146 crossfostered pups. At P7, all pups underwent unilateral common carotid artery ligation followed by 50 min of hypoxia (8% O2, 36°C). Immediately after this mild insult, the pups were randomized to post-insult normothermia or HT treatment. Pups were culled at P14. Injury was assessed by area loss of the ipsilateral hemisphere and histopathology scoring of the hippocampus, cortex, thalamus, and basal ganglia. Crossfostered pups had double the injury compared to non-crossfostered pups irrespective of the treatment group. Hypothermic neuroprotection was statistically significant, but with a smaller and less consistent effect in crossfostered pups (relative neuroprotection 16% vs. 31% in non-crossfostered). These results demonstrate hypothermic neuroprotection following a mild HI insult. A representative subset of 41 animals was also assessed for evidence of microglial reactivity; however, no detectable difference in microglial reactivity was observed between any of the groups. In conclusion, crossfostering alters outcomes in our established model through reduced insult tolerance and variable neuroprotection. Crossfostering as a common breeding practice is a largely unexplored variable in animal research that may result in invalid research conclusions if inadequately adjusted for by larger group sizes. As a result, crossfostering is likely to be inconsistent with the principles of replacement, reduction, and refinement.

Debate continues in this journal on the climate impacts of burning woody biomass from forests. A recent review by Cowie et al. (2021, GCB Bioenergy , 13(8), 1210–1231) addressed what it called ‘misconceptions’ in papers by us and other authors that examined issues of carbon debt and when burning forest biomass for energy could have a net climate benefit. This letter re‐emphasizes the critical importance of the time dimension in assessing impacts, and takes particular issue with Cowie et al's lack of concern over substantial delays in reducing emissions and increasing the risks of crossing climate tipping points.

BACKGROUND:Hypothermia-treated and intubated infants with moderate or severe hypoxic-ischemic encephalopathy (HIE) usually receive morphine for sedation and analgesia (SA) during therapeutic hypothermia (TH) and endotracheal ventilation. Altered drug pharmacokinetics in this population increases the risk of drug accumulation. Opioids are neurotoxic in preterm infants. In term infants undergoing TH, the long-term effects of morphine exposure are unknown. We examined the effect of opioid administration during TH on neurodevelopmental outcome and time to extubation after sedation ended. METHODS:In this prospectively collected population-based cohort of 282 infants with HIE treated with TH (2007-2017), the cumulative opioid dose of morphine and equipotent fentanyl (10-60 µg/kg/h) administered during the first week of life was calculated. Clinical outcomes and concomitant medications were also collected. Of 258 survivors, 229 underwent Bayley-3 neurodevelopmental assessments of cognition, language and motor function at 18-24 months. Multivariate stepwise linear regression analysis was used to examine the relation between cumulative opioid dose and Bayley-3 scores. Three severity-groups (mild-moderate-severe) were stratified by early (<6 h) amplitude-integrated electroencephalography (aEEG) patterns. FINDINGS:The cumulative dose of opioid administered as SA during TH was median (IQR) 2121 µg/kg (1343, 2741). Time to extubation was independent of SA dose (p > 0.2). There was no significant association between cumulative SA dose and any of the Bayley-3 domains when analysing the entire cohort or any of the aEEG severity groups. INTERPRETATION:Higher cumulative opioid doses in TH-treated infants with HIE was not associated with worse Bayley-3 scores at 18-24 months of age. FUNDING:The Bristol cooling program was funded by the Children's Medical Research Charity SPARKS managing donations for our research from the UK and US, the UK Moulton Foundation, the Lærdal Foundation for Acute Medicine in Norway and the Norwegian Research Council (JKG).

Background: Binary prediction-models for outcome [death, cognition, presence and severity of cerebral palsy (CP)], using MRI and early clinical data applicable for individual outcome prediction have not been developed. Methods: From Dec 1(s)(t) 2006 until Dec 31(st) 2013, we recruited 178 infants into a population-based cohort with moderate or severe hypoxic-ischaemic encephalopathy (HIE) including postnatal collapse (PNC, n = 12) and additional diagnoses (n = 12) using CoolCap/TOBY-trial entry-criteria including depressed amplitude-integrated EEG (aEEG). Early clinical/biochemical variables and MRI scans (median day 8) were obtained in 168 infants. Injury severity was scored for cortex, basal ganglia/thalami (BGT), white matter (WM) and posterior limb of the internal capsule, summating to a total injury score (TIS, range 0-11). Outcome was categorized as adverse or favourable at 18-24 months from Bayley-III domains (cut-off 85) and neurological examination including CP classification. Findings: HIE and entry-aEEG severity were stable throughout the study. Outcome was favourable in 133/178 infants and adverse in 45/178: 17 died, 28 had low Cognition/Language scores, (including 9 with severe CP and 6 mild); seven had mild CP with favourable cognitive outcome. WMxBGT product scores and TIS were strong outcome predictors, and prediction improved when clinical/biochemical variables were added in binary logistic regression. The Positive Predictive Value for adverse outcome was 88%, increasing to 95% after excluding infants with PNC and additional diagnoses. Using WMxBGT in the regression predicted 8 of the 9 children with severe CP. Interpretation: Binary logistic regression with WMxBGT or TIS and clinical variables gave excellent outcome prediction being 12% better than single variable cross-tabulation. Our MRI scoring and regression models are readily accessible and deserve investigation in other cohorts for group and individual prediction. (C) 2021 The Authors. Published by Elsevier Ltd.

Background: Successful cardiopulmonary resuscitation after drowning or avalanche is often attributed to hypothermia-induced decrease in metabolism, which adapts the oxygen demand to the amount supplied under cardiac compression. Four decades ago, we speculated if oxygen-sparing mechanisms like those found in marine mammals, may improve cerebral oxygenation during acute airway blockade in humans. We investigated hemodynamic changes during steady state ergometer cycling with intermittent periods of apnea and face immersion (AFI) in ice-cold water. During AFI, heart rate (HR) dropped by 58% whereas average blood velocity (ABV) determined by means of a Doppler ultrasound velocity meter (UNIDOP University of Oslo, Oslo, Norway) fell by 85% in the radial artery and rose by 67% in the vertebral artery. Similar changes occured in radial artery ABV, albeit more slowly, when the test subject only held his breath while cycling. When he breathed via a snorkel during face immersion, HR remained unchanged while radial artery ABV fell transiently and subsequently returned to its pre-immersion level. These findings later were confirmed by other investigators. Moreover, a recent study revealed that the seal even has a system for selective brain cooling during the dive. Conclusion: Our research has confirmed prioritized cerebral circulation during AFI in cold water. We hypothesize that these changes may improve brain oxygenation due both to greater blood flow and possibly also to faster brain cooling, as demonstrated in diving seals.

Changes in the body condition of Antarctic minke whales ( Balaenoptera bonaerensis ) have been investigated in a number of studies, but remain contested. Here we provide a new analysis of body condition measurements, with particularly careful attention to the statistical model building and to model selection issues. We analyse body condition data for a large number (4704) of minke whales caught between 1987 and 2005. The data consist of five different variables related to body condition (fat weight, blubber thickness and girth) and a number of temporal, spatial and biological covariates. The body condition variables are analysed using linear mixed-effects models, for which we provide sound biological motivation. Further, we conduct model selection with the focused information criterion (FIC), reflecting the fact that we have a clearly specified research question, which leads us to a clear focus parameter of particular interest. We find that there has been a substantial decline in body condition over the study period (the net declines are estimated to 10% for fat weight, 7% for blubber thickness and 3% for the girth). Interestingly, there seems to be some differences in body condition trends between males and females and in different regions of the Antarctic. The decline in body condition could indicate major changes in the Antarctic ecosystem, in particular, increased competition from some larger krill-eating whale species.

A central point of disagreement, in certain long-standing discussions about a particular whaling dataset in the Scientific Committee of the International Whaling Commission, has directly involved model selection issues for linear mixed effect models. The biological question under discussion is associated with a clearly defined parameter of primary interest, a focus parameter, which makes model selection with the Focused Information Criterion (FIC) more appropriate than other selection methods. Since the existing FIC methodology has not covered the case of linear mixed effects models, this article sets up the required framework and develops the necessary formulae for the relevant FIC. Our new criterion requires the asymptotic distribution of estimators derived for a given candidate linear mixed model but with behaviour examined under a wider linear mixed model. These results, needed here to build our FIC, also have independent interest.

Therapeutic hypothermia (HT) is standard care for term infants with hypoxic–ischaemic (HI) encephalopathy. However, the efficacy of HT in preclinical models, such as the Vannucci model of unilateral HI in the newborn rat, is often greater than that reported from clinical trials. Here, we report a meta-analysis of data from every experiment in a single laboratory, including pilot data, examining the effect of HT in the Vannucci model. Across 21 experiments using 106 litters, median (95% CI) hemispheric area loss was 50.1% (46.0–51.9%; n = 305) in the normothermia group, and 41.3% (35.1–44.9%; n = 317) in the HT group, with a bimodal injury distribution. Median neuroprotection by HT was 17.6% (6.8–28.3%), including in severe injury, but was highly-variable across experiments. Neuroprotection was significant in females ( p < 0.001), with a non-significant benefit in males ( p = 0.07). Animals representing the median injury in each group within each litter (n = 277, 44.5%) were also analysed using formal neuropathology, which showed neuroprotection by HT throughout the brain, particularly in females. Our results suggest an inherent variability and sex-dependence of the neuroprotective response to HT, with the majority of studies in the Vannucci model vastly underpowered to detect true treatment effects due to the distribution of injury.

The authors have no conflict of interests.

Plague has a long history on the European continent, with evidence of the disease dating back to the Stone Age. Plague epidemics in Europe during the First and Second Pandemics, including the Black Death, are infamous for their widespread mortality and lasting social and economic impact. Yet, Europe still experienced plague outbreaks during the Third Pandemic, which began in China and spread globally at the end of the nineteenth century. The digitization of international records of notifiable diseases, including plague, has enabled us to retrace the introductions of the disease to Europe from the earliest reported cases in 1899, to its disappearance in the 1940s. Using supplemental literature, we summarize the potential sources of plague in Europe and the transmission of the disease, including the role of rats. Finally, we discuss the international efforts aimed at prevention and intervention measures, namely improved hygiene and sanitation, that ultimately led to the disappearance of plague in Europe.

An important neonatal hypothermia (HT) trial on hypoxic-ischemic-encephalopathy was published in November 2017 by Laptook and the NICHD group (1). One hundred and sixty-eight newborn term infants who failed the 6 hour time-window for HT were recruited by 21 centers over an 8 year period into a trial of HT versus normothermia (NT) if they were >6h and <24 hours old. The median postnatal age at start of HT was 16 hours. The infants were cooled for 96 hours, 24 hours longer than the standard 72 hour duration. Survivors were examined at 18-22 months using the Bayley Scales of Infant Development III and a neurological examination. Outcome data were available for 157 infants including 18 who died (78 HT - 19 with poor outcome, 79 NT - 22 with poor outcome). Clearly, any outcome difference between the HT and NT groups must be small, and not significant (p≈0.75). However, the authors conclude, based on Bayesian analyses, that "among term infants with hypoxic-ischemic encephalopathy hypothermia initiated at 6 to 24 hours after birth compared with noncooling resulted in a 76% probability of any reduction in death or disability". This article is protected by copyright. All rights reserved.

We would like to thank Laptook et al. 1 for their response to our 'Major concerns about late hypothermia study' 2. However, their response suggests that the difference between their opinion and ours arises because we are using frequentist statistics and they are using Bayesian. This is not the case. There is indeed general concern at present about the potential misuse of p-values in frequentist statistical practice. We agree that generally in situations where a limited number of observations are available, the usual frequentist requirement for the significance probability to be lower than 0.05 is too strict. Results with a significance probability of 0.10 or even 0.15 may also give valuable information, and correspondingly a confidence interval (frequentist) or credibility interval (Bayesian) of 0.95 is sometimes too strict. The heart of the matter is whether the observation that 19 of 78 neonates in group 1 (with cooling initiated in the time window from 6 to 24 hours after birth) showed adverse outcomes can be said to indicate that the associated probability p1 is smaller than the corresponding probability p0 in the control group, where 22 of 79 showed adverse outcomes. The original JAMA paper 3 discussed this in terms of the relative risk rr = p1/p0, and the question is whether there are any grounds to claim, with any meaningful confidence or credibility (to use the relevant frequentist and Bayesian terms), that rr is smaller than 1. Our primary analysis was indeed frequentist, demonstrating that with sample sizes 79 and 78 there can be no meaningful statistical difference between the probability estimates 19/78 = 0.244 and 22/79 = 0.278. The close proximity of these two estimates can be assessed in several ways, including a p-value far above the customary levels for significance (p = 0.75), and a confidence curve with the value rr = 1 in the middle with a 95 per cent confidence interval (0.51, 1.48) (see Fig. 1 in our previous communication (2)). We have nothing against Bayesian analyses in general, and we agree that Laptook et al.'s 'neutral' unimodal prior with rr = 1 is sensible if no prior knowledge on late cooling is available. The detailed shape and especially the tails of this prior probability distribution are of course rather uncertain. As our figure clearly shows, Laptook et al.'s results give little support for the claim that p1 is smaller than p0 (i.e. that the relative risk parameter rr = p1/p0 above is smaller than 1). We have also performed a sensitivity analysis on the results of the trial. We moved two infants from the control group to the cooled group, so that the outcome was death or disability for 21 of 78 infants in the cooled group and 20 of 79 in the control group. These results would indicate a slightly better outcome for the control group, which is certainly possible if there is no real difference between the two groups. The figure displays Laptook et al.'s Bayesian prior probability distribution (in red) and two posterior probability distributions (in black) for the rr parameter. The solid black curve is the posterior using the observed data, while the dashed black curve is the posterior using the hypothetical outcomes from the sensitivity analysis. The 95 per cent credibility intervals for rr are (0.61, 1.40) and (0.68, 1.58), respectively, for the two posterior distributions. rr = 1.00 is close to the middle (median) in all three cases. Even intervals with 70% credibility or less would cover rr = 1.00 in all three distributions, indicating that there is no real difference between the two groups. In the JAMA paper Laptook et al. 3 write 'The probability that death or disability in cooled infants was at least 1, 2, or 3% less than non-cooled infants was 71, 64, and 56%, respectively', and further: cooling 'compared with non-cooling resulted in a 76% probability of any reduction in death or disability'. Unfortunately, we have not been able to reproduce these numbers using Laptook et al.'s 'neutral' prior. According to our Bayesian calculations, the probability that death or disability in cooled infants was at least 1, 2, or 3% less than in non-cooled infants was 64, 62 and 60%, respectively, and cooling resulted in a 65% probability of any reduction in death or disability. Using the posterior distribution from the sensitivity analysis, the probabilities were 41, 39, 37 and 43%, respectively. Two observations can be made from these numbers. There is always a positive probability that death and disability in cooled infants is less than in non-cooled infants, even when the trial results indicate the opposite, but these probabilities vary greatly with small changes in the real outcome. We also see that the two posterior distributions are not very different from the prior distribution. In fact, they are heavily influenced by the prior and only to a limited degree by the results from the trial. The probabilities in the tails of the posterior distribution are also strongly influenced by the shape and width of the prior distribution, of which we have limited knowledge. The very uncertain tail probabilities in the posterior distribution should therefore definitely not be used as arguments for late cooling. If the times when the cooling started had been given for all infants, other relevant statistical analyses could have been performed [e.g. logistic regression with time as a covariate or a Bayesian analysis with the results from late cooling of rat pups and foetal sheep as basis for a prior 2]. Although only tested in rats, one study showed that very severe injury increased more if cooling started 12 hour after the experimental insult 4. The current patient cohorts undergoing therapeutic hypothermia, including that in Laptook et al.'s 3 'Late hypothermia trial' are all milder than the original trial cohorts that showed that therapeutic hypothermia was effective. As an example; in the 2005 NICHD whole body cooling trial, the non-cooled group had 37% mortality and 40% disability in survivors 5. In the late hypothermia trial, the mortality in the non-cooled group was 11, and 19% of the survivors had disabilities 3. We do not agree that there is evidence for suggesting starting hypothermia treatment late. Also, one does not know how high the risk for harm would be 6 if one expose rather mild HIE infants to 3 days of cooling and intensive care. The authors have no conflict of interests. Funding supporting work on therapeutic hypothermia was received by The Wellcome Trust, UK (RJ 3445 [059061/Z/ 99/A]), The Norwegian Research Council and Medical Research Council, UK (G0100126 (2002), G0801320 (2009)).