Resveratrol pretreatment protects rat brain from cerebral ischemic damage via a sirtuin 1-uncoupling protein 2 pathway

Resveratrol is a natural polyphenol found in grapes and wine and has been associated with protective effects against cardiovascular diseases. In vitro, both resveratrol preconditioning (RPC) and ischemic preconditioning (IPC) require activation of sirtuin 1 (SIRT1), a nicotinamide adenine dinucleotide (NAD(+))-dependent deacetylase, to induce neuroprotection against cerebral ischemia. In the present study, we tested two hypotheses: (a) that neuroprotection against cerebral ischemia can be induced by RPC in vivo; and (b) that RPC neuroprotection involves alterations in mitochondrial function via the SIRT1 target mitochondrial uncoupling protein 2 (UCP2). IPC was induced by 2 min of global ischemia (temporary bilateral carotid artery occlusion with hypotension), and RPC, by i.p. injection of resveratrol at 10, 50 and 100 mg/kg dosages. Forty-eight hours later, we compared the neuroprotective efficacy of RPC and IPC in vulnerable cornu ammonis 1 hippocampal pyramidal neurons using a rat model of asphyxial cardiac arrest (ACA). SIRT1 activity was measured using a SIRT1-specific fluorescent enzyme activity assay. In hippocampal mitochondria isolated 48 h after IPC or RPC, we measured UCP2 levels, membrane potential, respiration, and the mitochondrial ATP synthesis efficiency (ADP/O ratio). Both IPC and RPC induced tolerance against brain injury induced by cardiac arrest in this in vivo model. IPC increased SIRT1 activity at 48 h, while RPC increased SIRT1 activity at 1 h but not 48 h after treatment in hippocampus. Resveratrol significantly decreased UCP2 levels by 35% compared to sham-treated rats. The SIRT1-specific inhibitor sirtinol abolished the neuroprotection afforded by RPC and the decrease in UCP2 levels. Finally, RPC significantly increased the ADP/O ratio in hippocampal mitochondria reflecting enhanced ATP synthesis efficiency. In conclusion, in vivo resveratrol pretreatment confers neuroprotection similar to IPC via the SIRT1-UCP2 pathway.

Unnatural sudden infant death

AIM

To identify features to help paediatricians differentiate between natural and unnatural infant deaths.

METHOD

Clinical features of 81 children judged by criminal and family courts to have been killed by their parents were studied. Health and social service records, court documents, and records from meetings with parents, relatives, and social workers were studied.

RESULTS

Initially, 42 children had been certified as dying from sudden infant death syndrome (SIDS), and 29 were given another cause of natural death. In 24 families, more than one child died; 58 died before the age of 6 months and most died in the afternoon or evening. Seventy per cent had experienced unexplained illnesses; over half were admitted to hospital within the previous month, and 15 had been discharged within 24 hours of death. The mother, father, or both were responsible for death in 43, five, and two families, respectively. Most homes were disadvantaged--no regular income, receiving income support--and mothers smoked. Half the perpetrators had a history of somatising or factitious disorder. Death was usually by smothering and 43% of children had bruises, petechiae, or blood on the face.

CONCLUSIONS

Although certain features are indicative of unnatural infant death, some are also associated with SIDS. Despite the recent reduction in numbers of infants dying suddenly, inadequacies in the assessment of their deaths exist. Until a thorough postmortem examination is combined with evaluation of the history and circumstances of death by an experienced paediatrician, most cases of covert fatal abuse will go undetected. The term SIDS requires revision or abandonment.

The constriction of the ductus arteriosus caused by oxygen and by asphyxia in newborn lambs

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Hypothermic reperfusion after cardiac arrest augments brain-derived neurotrophic factor activation

Induction of mild hypothermia improves neurologic outcome after global cerebral ischemia. This study measured levels of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in hippocampal tissue of rats after resuscitation from 8 minutes of normothermic, asphyxial cardiac arrest. After resuscitation, rats were maintained either at normal temperature (37 degrees C) or cooled to mild hypothermia (33 degrees C, beginning 60 minutes after resuscitation). After 12 or 24 hours, neurotrophin levels in hippocampus were measured by immunoblotting. Ischemia and reperfusion increased hippocampal levels of BDNF. Induction of hypothermia during reperfusion potentiated the increase in BDNF after 24 hours, but not after 12 hours. Levels of NGF were not increased by postresuscitation hypothermia. Hypothermia also increased tissue levels and tyrosine phosphorylation of TrkB, the receptor for BDNF. Increased BDNF levels were correlated with activation of the extracellularly regulated kinase (ERK), a downstream element in the signal transduction cascade induced by BDNF. In contrast to the many deleterious processes during ischemia and reperfusion that are inhibited by induced hypothermia, increasing BDNF levels is a potentially restorative process that is augmented. Increased activation of BDNF signaling is a possible mechanism by which mild hypothermia is able to reduce the neuronal damage typically occurring after cardiac arrest.

Discerning suicide in drug intoxication deaths: Paucity and primacy of suicide notes and psychiatric history

OBJECTIVE

A paucity of corroborative psychological and psychiatric evidence may be inhibiting detection of drug intoxication suicides in the United States. We evaluated the relative importance of suicide notes and psychiatric history in the classification of suicide by drug intoxication versus firearm (gunshot wound) plus hanging/suffocation-the other two major, but overtly violent methods.

METHODS

This observational multilevel (individual/county), multivariable study employed a generalized linear mixed model (GLMM) to analyze pooled suicides and undetermined intent deaths, as possible suicides, among the population aged 15 years and older in the 17 states participating in the National Violent Death Reporting System throughout 2011-2013. The outcome measure was relative odds of suicide versus undetermined classification, adjusted for demographics, precipitating circumstances, and investigation characteristics.

RESULTS

A suicide note, prior suicide attempt, or affective disorder was documented in less than one-third of suicides and one-quarter of undetermined deaths. The prevalence gaps were larger among drug intoxication cases than gunshot/hanging cases. The latter were more likely than intoxication cases to be classified as suicide versus undetermined manner of death (adjusted odds ratio [OR], 41.14; 95% CI, 34.43-49.15), as were cases documenting a suicide note (OR, 33.90; 95% CI, 26.11-44.05), prior suicide attempt (OR, 2.42; 95% CI, 2.11-2.77), or depression (OR, 1.61; 95% CI, 1.38 to 1.88), or bipolar disorder (OR, 1.41; 95% CI, 1.10-1.81). Stratification by mechanism/cause intensified the association between a note and suicide classification for intoxication cases (OR, 45.43; 95% CI, 31.06-66.58). Prior suicide attempt (OR, 2.64; 95% CI, 2.19-3.18) and depression (OR, 1.48; 95% CI, 1.17-1.87) were associated with suicide classification in intoxication but not gunshot/hanging cases.

CONCLUSIONS

Without psychological/psychiatric evidence contributing to manner of death classification, suicide by drug intoxication in the US is likely profoundly under-reported. Findings harbor adverse implications for surveillance, etiologic understanding, and prevention of suicides and drug deaths.

Effects of Experimental Congestive Heart Failure, Ouabain, and Asphyxia on the High-Energy Phosphate and Creatine Content of the Guinea Pig Heart

The left ventricles of guinea pigs have been assayed for adenosine triphosphate, adenosine diphosphate, adenylic acid, phosphorylcreatine, free creatine, and inorganic phosphate. These determinations have been made under various experimental conditions which affect the performance of the heart in vivo, such as experimental congestive heart failure, acute asphyxia, and the influence of the cardiac glycoside, ouabain. In 20 guinea pigs with experimental congestive heart failure, sacrificed 1 to 18 days after surgically producing a coarctation of the ascending aorta, a significant fall in PC (54 per cent), ATP (24 per cent), and total creatine (34 per cent) was observed. The extent of the loss of high-energy phosphate compounds and total creatine paralleled the severity of cardiac failure as determined by abnormal intraventricular pressure pulses, ventricular hypertrophy, and gross and microscopic pathology. In animals with experimental congestive heart failure, the cardiac glycoside ouabain produced significant slowing of the heart, a positive inotropic effect, and a lowering of abnormally high right ventricular systolic and left ventricular diastolic pressures. At the height of the response to ouabain, there was a further fall in PC to 25 per cent of normal without any change in ATP concentration. The positive inotropic action of ouabain is, therefore, not due to an ability of the drug to increase high-energy phosphate levels in failing heart muscle. Acute asphyxia produces a very rapid fall in the PC concentration (85 per cent lost in two minutes) and a much slower fall in ATP (33 per cent lost in eight minutes). Recovery of normal mechanical activity, after a period of asphyxia, by rebreathing occurs with little, if any, restoration of ATP and at a time when the PC concentration is only about 25 per cent of normal. These experiments indicate that steady-state levels of high-energy phosphate compounds are not as important in determining the mechanical capacity of the heart as are their rates of synthesis.

Bumpus in the snake den: effects of sex, size, and body condition on mortality of red-sided garter snakes

Huge breeding aggregations of red-sided garter snakes (Thamnophis sirtalis parietalis) at overwintering dens in Manitoba provide a unique opportunity to identify sources of mortality and to clarify factors that influence a snake's vulnerability to these factors. Comparisons of sexes, body sizes, and body condition of more than 1000 dead snakes versus live animals sampled at the same time reveal significant biases. Three primary sources of mortality were identified. Predation by crows, Corvus brachyrhynchos (590 snakes killed), was focussed mostly on small snakes of both sexes. Crows generally removed the snake's liver and left the carcass, but very small snakes were sometimes brought back to the nest. Suffocation beneath massive piles of other snakes within the den (301 dead animals) involved mostly small males and (to a lesser extent) large females; snakes in poor body condition were particularly vulnerable. Many emaciated snakes (n = 142, mostly females) also died without overt injuries, probably due to depleted energy reserves. These biases in vulnerability are readily interpretable from information on behavioral ecology of the snakes. For example, sex biases in mortality reflect differences in postemergence behavior and locomotor capacity, the greater attractiveness of larger females to males, and the high energy costs of reproduction for females.

Cardiac output distribution in response to hypoxia in the chick embryo in the second half of the incubation time

1. The fetus develops cardiovascular adaptations to protect vital organs in situations such as hypoxia and asphyxia. These include bradycardia, increased systemic blood pressure and redistribution of the cardiac output. The extent to which they involve maternal or placenta influences is not known. The objective of the present work was to study the cardiac output distribution in response to hypoxia in the chick embryo, which is independent of the mother. 2. Fertilized eggs were studied at three incubation times (10-13 days, 14-16 days and 17-19 days of a normal incubation time of 21 days). Eggs were placed in a Plexiglass box in which the oxygen concentration could be changed. Eggs were opened at the air cell and a chorioallantoic vein was catheterized. Cardiac output distribution was measured with 15 micron fluorescent microspheres injected during normoxia, during the last minute of a 5 min period of hypoxia and after 5 min of subsequent reoxygenation. 3. Hypoxia caused a redistribution of the cardiac output in favour of heart (+17 to +160 % of baseline) and brain (+21 to +57 % of baseline) at the expense of liver (-3 to -65 % of baseline), yolk-sac (-46 to -77 % of baseline) and carcass (-6 to -33 % of baseline). 4. The magnitude of the changes in cardiac output distribution to the heart, brain, liver and carcass in response to hypoxia increased with advancing incubation time. 5. The data demonstrate the development of a protective redistribution of the cardiac output in response to hypoxia in the chick embryo from day 10 of incubation.