Apoptosis and necroptosis occur in the different brain regions of hippocampus in a rat model of hypoxia asphyxia

AIM OF THE STUDY

Hypoxic-ischemic encephalopathy (HIE) is a major cause of newborn brain injury. Apoptosis and necroptosis are two forms of cell death which may occur in HIE but reported data are yet limited. This study investigates the expression of receptor interacting protein kinase (RIPK) 1 and 3, and caspase3, the key modulators of necroptosis and apoptosis, respectively, in a model of HIE to determine whether both forms of cell death occur in the corresponding brain regions.

MATERIALS AND METHODS

Postneonatal day 7 Sprague-Dawley rats were subjected to right carotid artery ligation followed by hypoxia or subjected to skin incision under surgical anesthesia without ligation and hypoxia. Neuroglioma (H4) cell was cultured and subjected to 24 h hypoxic insults. Necrostatin-1, a RIPK1 inhibitor, was administered in both in vivo and in vitro settings before insult.

RESULTS

After hypoxic-ischemic insults, both RIPK1 and RIPK3 expression were significantly increased in the region of hippocampal dentate gyrus in the injurious hemisphere. However, cleaved caspase3 was significantly increased in the hippocampal cornu ammonis 1 region in the injurious hemisphere. After hypoxic insults, RIPK1 and RIPK3 expression was also found in H4 cells. In addition, it was identified that the increased RIPK1 and RIPK3 can be inhibited by necrostatin-1 in both in vivo and in vitro.

CONCLUSIONS

These data indicated that apoptosis and necroptosis occur in different brain regions of hippocampus in a model of HIE which may suggest that strategies to prevent each form of neuronal death is valuable to be developed.

HSP70-mediated neuroprotection by combined treatment of valproic acid with hypothermia in a rat asphyxial cardiac arrest model

It has been reported that valproic acid (VPA) combined with therapeutic hypothermia can improve survival and neurologic outcomes in a rat asphyxial cardiac arrest model. However, neuroprotective mechanisms of such combined treatment of valproic acid with hypothermia remains unclear. We hypothesized that epigenetic regulation of HSP70 by histone acetylation could increase HSP70-mediated neuroprotection suppressed under hypothermia. Male Sprague-Dawley rats that achieved return of spontaneous circulation (ROSC) from asphyxial cardiac arrest were randomized to four groups: normothermia (37°C ± 1°C), hypothermia (33°C ± 1°C), normothermia + VPA (300 mg/kg IV initiated 5 minutes post-ROSC and infused over 20 min), and hypothermia + VPA. Three hours after ROSC, acetyl-histone H3 was highly expressed in VPA-administered groups (normothermia + VPA, hypothermia + VPA). Four hours after ROSC, HSP70 mRNA expression levels were significantly higher in normothermic groups (normothermia, normothermia + VPA) than in hypothermic groups (hypothermia, hypothermia + VPA). The hypothermia + VPA group showed significantly higher HSP70 mRNA expression than the hypothermia group. Similarly, at five hours after ROSC, HSP70 protein levels were significantly higher in normothermic groups than in hypothermic groups. HSP70 levels were significantly higher in the hypothermia + VPA group than in the hypothermia group. Only the hypothermia + VPA group showed significantly attenuated cleaved caspase-9 levels than the normothermia group. Hypothermia can attenuate the expression of HSP70 at transcriptional level. However, VPA administration can induce hyperacetylation of histone H3, leading to epigenetic transcriptional activation of HSP70 even in a hypothermic status. Combining VPA treatment with hypothermia may compensate for reduced activation of HSP70-mediated anti-apoptotic pathway.

Neonatal Mesenchymal Stem Cell Treatment Improves Myelination Impaired by Global Perinatal Asphyxia in Rats

The effect of perinatal asphyxia (PA) on oligodendrocyte (OL), neuroinflammation, and cell viability was evaluated in telencephalon of rats at postnatal day (P)1, 7, and 14, a period characterized by a spur of neuronal networking, evaluating the effect of mesenchymal stem cell (MSCs)-treatment. The issue was investigated with a rat model of global PA, mimicking a clinical risk occurring under labor. PA was induced by immersing fetus-containing uterine horns into a water bath for 21 min (AS), using sibling-caesarean-delivered fetuses (CS) as controls. Two hours after delivery, AS and CS neonates were injected with either 5 μL of vehicle (10% plasma) or 5 × 10⁴ MSCs into the lateral ventricle. Samples were assayed for myelin-basic protein (MBP) levels; Olig-1/Olig-2 transcriptional factors; Gglial phenotype; neuroinflammation, and delayed cell death. The main effects were observed at P7, including: (i) A decrease of MBP-immunoreactivity in external capsule, corpus callosum, cingulum, but not in fimbriae of hippocampus; (ii) an increase of Olig-1-mRNA levels; (iii) an increase of IL-6-mRNA, but not in protein levels; (iv) an increase in cell death, including OLs; and (v) MSCs treatment prevented the effect of PA on myelination, OLs number, and cell death. The present findings show that PA induces regional- and developmental-dependent changes on myelination and OLs maturation. Neonatal MSCs treatment improves survival of mature OLs and myelination in telencephalic white matter.

Model for the prediction of mechanical asphyxia as the cause of death based on four biological indexes in human cardiac tissue

Determination of mechanical asphyxia as the cause of death has always been difficult for forensic pathologists, particularly when signs of asphyxia are not obvious on the body. Currently, depending on only physical examination of corpses, pathologists must be cautious when making cause-of-death appraisals. In a previous study, four biomarkers-dual-specificity phosphatase 1 (DUSP1), potassium voltage-gated channel subfamily J member 2 (KCNJ2), miR-122, and miR-3185-were screened in human cardiac tissue from cadavers that died from mechanical asphyxia compared with those that died from craniocerebral injury, hemorrhagic shock, or other causes. Expression of the markers correlated with death from mechanical asphyxia regardless of age, environmental temperature, and postmortem interval. However, a single biological index is not an accurate basis for the identification of the cause of death. In this study, receiver operating characteristic curves of the ΔCq values of the four indexes were generated. The diagnostic accuracy of the indexes was judged according to their area under the curve (DUSP1: 0.773, KCNJ2: 0.775, miR-122: 0.667, and miR-3185: 0.801). Finally, a nomogram was generated, and single blind experiment was conducted to verify the cause of death of mechanical asphyxia.

Perinatal Infection: A Major Contributor to Efficacy of Cooling in Newborns Following Birth Asphyxia

Neonatal encephalopathy (NE) is a global burden, as more than 90% of NE occurs in low- and middle-income countries (LMICs). Perinatal infection seems to limit the neuroprotective efficacy of therapeutic hypothermia. Efforts made to use therapeutic hypothermia in LMICs treating NE has led to increased neonatal mortality rates. The heat shock and cold shock protein responses are essential for survival against a wide range of stressors during which organisms raise their core body temperature and temporarily subject themselves to thermal and cold stress in the face of infection. The characteristic increase and decrease in core body temperature activates and utilizes elements of the heat shock and cold shock response pathways to modify cytokine and chemokine gene expression, cellular signaling, and immune cell mobilization to sites of inflammation, infection, and injury. Hypothermia stimulates microglia to secret cold-inducible RNA-binding protein (CIRP), which triggers NF-κB, controlling multiple inflammatory pathways, including nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasomes and cyclooxygenase-2 (COX-2) signaling. Brain responses through changes in heat shock protein and cold shock protein transcription and gene-expression following fever range and hyperthermia may be new promising potential therapeutic targets.

Excess cerebral oxygen delivery follows return of spontaneous circulation in near-term asphyxiated lambs

Hypoxic-ischaemia renders the neonatal brain susceptible to early secondary injury from oxidative stress and impaired autoregulation. We aimed to describe cerebral oxygen kinetics and haemodynamics immediately following return of spontaneous circulation (ROSC) and evaluate non-invasive parameters to facilitate bedside monitoring. Near-term sheep fetuses [139 ± 2 (SD) days gestation, n = 16] were instrumented to measure carotid artery (CA) flow, pressure, right brachial arterial and jugular venous saturation (SaO2 and SvO2, respectively). Cerebral oxygenation (crSO2) was measured using near-infrared spectroscopy (NIRS). Following induction of severe asphyxia, lambs received cardiopulmonary resuscitation using 100% oxygen until ROSC, with oxygen subsequently weaned according to saturation nomograms as per current guidelines. We found that oxygen consumption did not rise following ROSC, but oxygen delivery was markedly elevated until 15 min after ROSC. CrSO2 and heart rate each correlated with oxygen delivery. SaO2 remained > 90% and was less useful for identifying trends in oxygen delivery. CrSO2 correlated inversely with cerebral fractional oxygen extraction. In conclusion, ROSC from perinatal asphyxia is characterised by excess oxygen delivery that is driven by rapid increases in cerebrovascular pressure, flow, and oxygen saturation, and may be monitored non-invasively. Further work to describe and limit injury mediated by oxygen toxicity following ROSC is warranted.

Stearic acid methyl ester affords neuroprotection and improves functional outcomes after cardiac arrest

Cardiac arrest causes neuronal damage and functional impairments that can result in learning/memory dysfunction after ischemia. We previously identified a saturated fatty acid (stearic acid methyl ester, SAME) that was released from the superior cervical ganglion (sympathetic ganglion). The function of stearic acid methyl ester is currently unknown. Here, we show that SAME can inhibit the detrimental effects of global cerebral ischemia (i.e. cardiac arrest). Treatment with SAME in the presence of asphyxial cardiac arrest (ACA) revived learning and working memory deficits. Similarly, SAME-treated hippocampal slices after oxygen-glucose deprivation inhibited neuronal cell death. Moreover, SAME afforded neuroprotection against ACA in the CA1 region of the hippocampus, reduced ionized calcium-binding adapter molecule 1 expression and inflammatory cytokines/chemokines, with restoration in mitochondria respiration. Altogether, we describe a unique and uncharted role of saturated fatty acids in the brain that may have important implications against cerebral ischemia.

Novel application of amino-acid buffered solution for neuroprotection against ischemia/reperfusion injury

Ischemic neuron loss contributes to brain dysfunction in patients with cardiac arrest (CA). Histidine–tryptophan–ketoglutarate (HTK) solution is a preservative used during organ transplantation. We tested the potential of HTK to protect neurons from severe hypoxia (SH) following CA. We isolated rat primary cortical neurons and induced SH with or without HTK. Changes in caspase-3, hypoxia-inducible factor 1-alpha (HIF-1α), and nicotinamide adenine dinucleotide phosphate oxidase-4 (NOX4) expression were evaluated at different time points up to 72 h. Using a rat asphyxia model, we induced CA-mediated brain damage and then completed resuscitation. HTK or sterile saline was administered into the left carotid artery. Neurological deficit scoring and mortality were evaluated for 3 days. Then the rats were sacrificed for evaluation of NOX4 and H₂O₂ levels in blood and brain. In the in vitro study, HTK attenuated SH- and H₂O₂-mediated cytotoxicity in a volume- and time-dependent manner, associated with persistent HIF-1α expression and reductions in procaspase-3 activation and NOX4 expression. The inhibition of HIF-1α abrogated HTK’s effect on NOX4. In the in vivo study, neurological scores were significantly improved by HTK. H₂O₂ level, NOX4 activity, and NOX4 gene expression were all decreased in the brain specimens of HTK-treated rats. Our results suggest that HTK acts as an effective neuroprotective solution by maintaining elevated HIF-1α level, which was associated with inhibited procaspase-3 activation and decreased NOX4 expression.

Acute LPS sensitization and continuous infusion exacerbates hypoxic brain injury in a piglet model of neonatal encephalopathy

Co-existing infection/inflammation and birth asphyxia potentiate the risk of developing neonatal encephalopathy (NE) and adverse outcome. In a newborn piglet model we assessed the effect of E. coli lipopolysaccharide (LPS) infusion started 4 h prior to and continued for 48 h after hypoxia on brain cell death and systemic haematological changes compared to LPS and hypoxia alone. LPS sensitized hypoxia resulted in an increase in mortality and in brain cell death (TUNEL positive cells) throughout the whole brain, and in the internal capsule, periventricular white matter and sensorimotor cortex. LPS alone did not increase brain cell death at 48 h, despite evidence of neuroinflammation, including the greatest increases in microglial proliferation, reactive astrocytosis and cleavage of caspase-3. LPS exposure caused splenic hypertrophy and platelet count suppression. The combination of LPS and hypoxia resulted in the highest and most sustained systemic white cell count increase. These findings highlight the significant contribution of acute inflammation sensitization prior to an asphyxial insult on NE illness severity.

Activation of Sigma-1 Receptor by Cutamesine Attenuates Neuronal Apoptosis by Inhibiting Endoplasmic Reticulum Stress and Mitochondrial Dysfunction in a Rat Model of Asphyxia Cardiac Arrest

BACKGROUND

Global cerebral ischemic/reperfusion (I/R) injury after cardiac arrest (CA) is a major cause of mortality and morbidity in survivors of resuscitation. We utilized a rat model of asphyxia CA to explore the functional effects and mechanisms of Sigma-1 receptor (Sig-1R) activation in cerebral protection using the Sig-1R agonist cutamesine (SA-4503).

METHODS

After resuscitation, the surviving rats were randomly divided into three groups (n = 18 each): the cardiopulmonary resuscitation (CPR) group (0.9% saline at 1 mL/kg); the SA4503 low-dose group (1 mg/kg SA4503); and the SA4503 high-dose group (2.5 mg/kg SA4503). The neurological deficit scores were recorded, and the cerebral cortex was harvested for western blotting. Mitochondrial transmembrane potential, adenosine triphosphate (ATP) concentrations, calcium homeostasis, and mitochondrial ultrastructure were also studied.

RESULTS

The SA4503 treatment groups exhibited improved neurological outcomes compared with the CPR group. The protein levels of caspase-3 and the endoplasmic reticulum stress markers C/EBP homologous protein and caspase-12 were lower in the SA4503 treatment groups compared with the CPR group. SA4503 treatment also normalized mitochondrial membrane potential, tissue ATP concentrations, intracellular Ca overload, and upregulated Sig-1R protein level compared with the CPR group. The SA4503 high dose treatment showed significant cerebral protective effects compared with the SA4503 low dose treatment. The therapeutic effect of SA4503 was dose-dependent.

CONCLUSIONS

CA downregulated Sig-1R protein expression. Activating Sig-1R using SA4503 protected against global cerebral I/R injury in a rat model of asphyxia CA by alleviating endoplasmic reticulum stress and mitochondrial dysfunction and eventually inhibiting neuronal apoptosis.

[Forensic medical diagnostics of intra-vitality of the strangulation mark by morphological methods]

The objective of the present study WaS to overview the current domestic and foreign literature concerning the up-to-date methods employed for the expert evaluation of intra-vitality of the strangulation mark. The secondary objective was to propose the new approaches for addressing this problem. The methods of expert diagnostics with a view to determining the time of infliction of injuries as exemplified by mechanical asphyxia are discussed. It is concluded that immunohistochemical and morphometric studies provide the most promising tools for the evaluation of intra-vitality of the strangulation mark for the purpose of forensic medical expertise.

Blood brain barrier is impermeable to solutes and permeable to water after experimental pediatric cardiac arrest

Pediatric asphyxial cardiac arrest (CA) results in unfavorable neurological outcome in most survivors. Development of neuroprotective therapies is contingent upon understanding the permeability of intravenously delivered medications through the blood brain barrier (BBB). In a model of pediatric CA we sought to characterize BBB permeability to small and large molecular weight substances. Additionally, we measured the percent brain water after CA. Asphyxia of 9 min was induced in 16-18 day-old rats. The rats were resuscitated and the BBB permeability to small (sodium fluorescein and gadoteridol) and large (immunoglobulin G, IgG) molecules was assessed at 1, 4, and 24 h after asphyxial CA or sham surgery. Percent brain water was measured post-CA and in shams using wet-to-dry brain weight. Fluorescence, gadoteridol uptake, or IgG staining at 1, 4h and over the entire 24 h post-CA did not differ from shams, suggesting absence of BBB permeability to these solutes. Cerebral water content was increased at 3h post-CA vs. sham. In conclusion, after 9 min of asphyxial CA there is no BBB permeability over 24h to conventional small or large molecule tracers despite the fact that cerebral water content is increased early post-CA indicating the development of brain edema. Evaluation of novel therapies targeting neuronal death after pediatric CA should include their capacity to cross the BBB.

Metabolic effects of perinatal asphyxia in the rat cerebral cortex

We reported previously that intrauterine asphyxia acutely affects the rat hippocampus. For this reason, the early effects of this injury were studied in the cerebral cortex, immediately after hysterectomy (acute condition) or following a recovery period at normoxia (recovery condition). Lactacidemia and glycemia were determined, as well as glycogen levels in the muscle, liver and cortex. Cortical tissue was also used to assay the ATP levels and glutamate uptake. Asphyxiated pups exhibited bluish coloring, loss of movement, sporadic gasping and hypertonia. However, the appearance of the controls and asphyxiated pups was similar at the end of the recovery period. Lactacidemia and glycemia were significantly increased by asphyxia in both the acute and recovery conditions. Concerning muscle and hepatic glycogen, the control group showed significantly higher levels than the asphyxic group in the acute condition and when compared with groups of the recovery period. In the recovery condition, the control and asphyxic groups showed similar glycogen levels. However, in the cortex, the control groups showed significantly higher glycogen levels than the asphyxic group, in both the acute and recovery conditions. In the cortical tissue, asphyxia reduced ATP levels by 70 % in the acute condition, but these levels increased significantly in asphyxic pups after the recovery period. Asphyxia did not affect glutamate transport in the cortex of both groups. Our results suggest that the cortex uses different energy resources to restore ATP after an asphyxia episode followed by a reperfusion period. This strategy could sustain the activity of essential energy-dependent mechanisms.

[Relation between PMI and FTIR spectral changes in asphyxiated rat's liver and spleen]

OBJECTIVE

Fourier transform infrared (FTIR) spectroscopy was applied to observe the postmortem degradation process in mechanical asphyxiated rat's liver and spleen for providing a new method of estimating PMI.

METHODS

Rats were sacrificed by mechanical asphyxia and cadavers were kept at (20 +/- 2) degrees C in a control chamber. The liver and spleen were sub-sampled from the same rat at intervals of 0-15 days postmortem and the data were measured by FTIR spectrometer. The different absorbance (A) ratios of peaks were calculated and the curve estimation analysis between absorbance ratios (x) and PMI (y) were performed to establish mathematical models by the statistical software.

RESULTS

The band absorbance ratios showed increase, decrease and stable with PMI. The cubic model functions showed the strongest correlation coefficient. Compared with the spleen, the liver showed a higher correlation coefficient. The A1541/A1396 of liver showed the highest correlation coefficient (r=0.966). After 6-7 days postmortem, band absorbance ratios showed a steady period.

CONCLUSION

FTIR spectroscopy can be a new and efficient method to estimate PMI within 7 days.

Maturation of the mitochondrial redox response to profound asphyxia in fetal sheep

Fetal susceptibility to hypoxic brain injury increases over the last third of gestation. This study examined the hypothesis that this is associated with impaired mitochondrial adaptation, as measured by more rapid oxidation of cytochrome oxidase (CytOx) during profound asphyxia. Methods: Chronically instrumented fetal sheep at 0.6, 0.7, and 0.85 gestation were subjected to either 30 min (0.6 gestational age (ga), n = 6), 25 min (0.7 ga, n = 27) or 15 min (0.85 ga, n = 17) of complete umbilical cord occlusion. Fetal EEG, cerebral impedance (to measure brain swelling) and near-infrared spectroscopy-derived intra-cerebral oxygenation (ΔHb = HbO₂ – Hb), total hemoglobin (THb) and CytOx redox state were monitored continuously. Occlusion was associated with profound, rapid fall in ΔHb in all groups to a plateau from 6 min, greatest at 0.85 ga compared to 0.6 and 0.7 ga (p<0.05). THb initially increased at all ages, with the greatest rise at 0.85 ga (p<0.05), followed by a progressive fall from 7 min in all groups. CytOx initially increased in all groups with the greatest rise at 0.85 ga (p<0.05), followed by a further, delayed increase in preterm fetuses, but a striking fall in the 0.85 group after 6 min of occlusion. Cerebral impedance (a measure of cytotoxic edema) increased earlier and more rapidly with greater gestation. In conclusion, the more rapid rise in CytOx and cortical impedance during profound asphyxia with greater maturation is consistent with increasing dependence on oxidative metabolism leading to earlier onset of neural energy failure before the onset of systemic hypotension.

[Relationship between PMI and fourier transform infrared spectral changes in muscle of rats after death caused by mechanical asphyxial]

OBJECTIVE

To observe the postmortem degradation process in rat myocardium and skeletal muscle using Fourier transform infrared (FTIR) spectroscopy and to provide a new method for estimating postmortem interval (PMI).

METHODS

Left ventricle and skeletal muscles of rats dying of mechanical asphyxiated were sampled at different PMIs. The changes of different chemical functional group in the myocardium and skeletal muscle samples were measured by FTIR spectroscopy. The different absorbance (A) ratios of peaks were calculated and the curve estimation analysis between absorbance ratios (x) and PMI (y) were performed to establish six mathematical models.

RESULTS

FTIR spectral absorption peak of rat myocardium and skeletal muscle showed three changes: increase, decrease and stable. The cubic model function showed the strongest correlation coefficient. The A1080/A1396 ratio of skeletal muscle showed the strongest correlation coefficient (r = 0.832) with more accurate determination of PMI.

CONCLUSION

FYIR spectroscopy can be potentially used as an effective method for estimating PMI in forensic practice using myocardium and skeletal muscle.

[Effects and mechanisms of heme oxygenase-1 on rats with postresuscitation myocardial dysfunction]

OBJECTIVE

To explore the effects and mechanisms of heme oxygenase-1 on rats with postresuscitation myocardial dysfunction.

METHODS

Male Sprague-Dawley rats were asphyxiated for 9 minutes and resuscitated. They were randomly divided into 4 groups: sham-operated, cardiopulmonary resuscitation (CPR), hemin and hemin + ZnPP (zinc protoporphyrin IX). Resuscitated groups had 2 observation points: 6 and 24 hours post-CPR (n = 8 for each time point). And the sham-operated group of 12 rats were divided in two observation points, according to 6 or 24 hours post-operation (n = 6 each). Hemodynamic was observed. The expression of heme oxygenase-1 (HO-1) in cardiac tissue was detected by Western blot. And the activity of cardiac homogenate superoxide dismutase (SOD) was determined by xanthine oxidase method and the level of malondialdehyde (MDA) measured by the thiobarbituric acid method. Nitrotyrosine protein expression in cardiac tissue was analyzed by immunohistochemistry.

RESULTS

(1) The mean blood pressure (MAP) significantly decreased in resuscitated groups after resuscitation (all P < 0.05). No difference existed between the subgroups. The scores of dP/dt40 and -dP/dt significantly decreased in CPR and hemin + ZnPP groups after resuscitation (all P < 0.05). But dP/dt40 in hemin group did not differ significantly after resuscitation and -dP/dt decreased only 0.5 hour and 1 hour post-resuscitation (3341.60 ± 524.85 and 3711.40 ± 502.39 vs 4284.20 ± 800.87, all P < 0.05). The scores of dP/dt40 and -dP/dt in hemin group at all time points post-resuscitation were significantly higher than those in CPR and hemin + ZnPP groups (all P < 0.05). (2) Compared with the sham-operated group, the HO-1 expression, MDA level and nitrotyrosine protein expression significantly increased while the activities of SOD decreased after resuscitation in the CPR, hemin and hemin + ZnPP groups (all P < 0.05). Compared with the CPR and hemin + ZnPP groups, the expression of HO-1 and the activity of SOD increased, while MDA level and nitrotyrosine protein expression were decreased in group hemin (all P < 0.05). No difference existed in the above indices between the CPR and hemin + ZnPP groups.

CONCLUSION

HO-1 can reduce myocardial oxidative stress injury after cardiopulmonary resuscitation and effectively improve post-resuscitation myocardial function in rats.

Somatostatin modulates generation of inspiratory rhythms and determines asphyxia survival

Breathing and the activity of its generator (the pre-Bötzinger complex; pre-BötC) are highly regulated functions. Among neuromodulators of breathing, somatostatin (SST) is unique: it is synthesized by a subset of glutamatergic pre-BötC neurons, but acts as an inhibitory neuromodulator. Moreover, SST regulates breathing both in normoxic and in hypoxic conditions. Although it has been implicated in the neuromodulation of breathing, neither the locus of SST modulation, nor the receptor subtypes involved have been identified. In this study, we aimed to fill in these blanks by characterizing the SST-induced regulation of inspiratory rhythm generation in vitro and in vivo. We found that both endogenous and exogenous SST depress all preBötC-generated rhythms. While SST abolishes sighs, it also decreases the frequency and increases the regularity of eupnea and gasping. Pharmacological experiments showed that SST modulates inspiratory rhythm generation by activating SST receptor type-2, whose mRNA is abundantly expressed in the pre-Bötzinger complex. In vivo, blockade of SST receptor type-2 reduces gasping amplitude and consequently, it precludes auto-resuscitation after asphyxia. Based on our findings, we suggest that SST functions as an inhibitory neuromodulator released by excitatory respiratory neurons when they become overactivated in order to stabilize breathing rhythmicity in normoxic and hypoxic conditions.

Euthanization methods influence cytokine mRNA expression levels in age 0 year Oncorhynchus mykiss

Significant differences in cytokine transcription were found between Oncorhynchus mykiss euthanized using the pharmacological agents MS-222 v. benzocaine and also when contrasting death induced by carbon dioxide asphyxiation v. physical methods (cervical dislocation). This study highlights the need to consider the potentially confounding effect of euthanization method on gene expression data.

Glutamate signaling in the pathophysiology and therapy of prenatal insults

Birth asphyxia and hypoxia-ischemia (HI) are important factors affecting the normal development and maturation of the central nervous system (CNS). Depending on the maturity of the brain, HI-induced damage at different ages is region-selective, the white matter (WM) peripheral to the lateral ventricles being selectively vulnerable to damage in premature infants. As a squeal of primary or secondary HI in the preterm infant, the brain injury comprises periventricular leukomalasia (PVL), accompanied by neuronal and axonal damage, which affects several brain regions. Premature delivery and improved neonatal intensive care have led to a survival rate of about 75% to 90% of infants weighting under 1500g both in Europe and in the United States. However, about 5-10% of these survivors exhibit cerebral palsy (CP), and many have cognitive, behavioral, attentional or socialization deficits. In this review, we first shortly discuss developmental changes in the expression of the excitatory glutamate receptors (GluRs), and then in more detail elucidate the contribution of GluRs to oligodendrocyte (OL) damage both in experimental models and in preterm human infants. Finally, therapeutic interventions targeted at GluRs at the young age are discussed in the light of results obtained from recent experimental HI animal models and from humans.

[The analysis of pericardial fluid in forensic practice]

Pericardial fluid is a kind of serous fluid in pericardial cavity. Because blood undergoes postmortem changes such as autolysis and putrefaction, vitreous humor is limited,cerebrospinal fluid is easily mixed with blood, pericardial fluid, on the other hand, exists in a closed cavity and can be hardly contaminated by postmortem changes, and also is easily obtained. Pericardial fluid not only plays an important role in clinic practice, but also is widely applicable in forensic practice. This paper briefly presented the properties of pericardial fluid and its clinical significance. It reviewed biochemical changes in decedents died of heart diseases, drowning and asphyxia, and explored the significance in medico-legal investigation. Moreover, application of pericardial fluid in forensic serology, forensic toxicological analysis and other fields were also discussed. Pericardial fluid analysis may provide important information for determination of the cause of death with further investigation concerning forensic applicability of pericardial fluid.

Troponin in newborns and pediatric patients

Cardiac troponin represents a sensitive and specific marker of ischemic myocardial damage in adult and neonatal populations. Cardiac function in neonates could be influenced by the severity of respiratory distress and its ventilatory management. This short review summarizes the experimental and clinical evidence regarding the role of cardiac troponin in assessment of cardiac function, in following findings: neonatal intensive care, respiratory distress syndrome, asphyxia, congenital heart disease and post cardiac surgery.

[Effect of Xinmailong on hypoxia-inducible factor-1alpha expression in neonatal rats with asphyxia]

OBJECTIVE

Xinmailong, a compound extracted from Periplaneta americana, is used for the treatment of cardiovascular diseases. This study investigated the effects of Xinmailong on myocardial hypoxia-inducible factor-1alpha (HIF-1alpha) and plasma endothelin-1(ET-1) levels in neonatal rats with asphyxia and explored the protection mechanism of Xinmailong in hypoxia-ischemic myocardial injury.

METHODS

Seven-day-old Sprague-Dawley rats were randomly divided into three groups (n=30 each): sham-operated, asphyxia, Xinmailong-treated asphyxia. Each group was randomly subdivided into three groups according to the observed time points: 6 hrs, 24 hrs and 72 hrs. Xinmailong (5 mg/kg) was intraperitoneally injected to the rats in the Xinmailong-treated group five minutes before asphyxia. Myocardial HIF-1alpha expression, and plasma ET-1 and creatine kinase (CK) levels were measured. The histopathologic changes of the myocardium were observed by hematoxylin-eosin staining.

RESULTS

Four rats died in the asphyxia group while only one died in the Xinmailong-treated group during the experiment. The plasma ET-1 and CK levels as well as myocardial HIF-1alpha expression increased at 6 hrs, reached a peak at 24 hrs, and declined at 72 hrs after asphyxia in the asphyxia group, being higher than that in the sham-operated group (P<0.01). Myocardial ischemia was observed in the three time points, and cell necrosis occurred at 24 hrs after asphyxia in the asphyxia group. Myocardial HIF-1alpha expression was positively correlated with plasma ET-1 levels (r=0.876, P<0.01). In the Xinmailong-treated group, plasma levels of CK and ET-1 as well as myocardial HIF-1alpha expression were significantly lower than those in the asphyxia group (P<0.01). Myocardial ischemia was alleviated and no cell necrosis was found in the Xinmailong-treated group.

CONCLUSIONS

Asphyxia leads to increase in myocardial HIF-1alpha expression and plasma levels of ET-1 and CK. Xinmailong can reduce the myocardial expression of HIF-1alpha and decrease plasma ET-1 levels, thus alleviating hypoxia-ischemic myocardial injury.

NEOSTRIATAL CYTOSKELETON CHANGES FOLLOWING PERINATAL ASPHYXIA: EFFECT OF HYPOTHERMIA TREATMENT

Long-term changes of different types of neurofilaments (NF) and glial fibrillar acid protein (GFAP) were studied in neostriatal rat subjected to perinatal asphyxia (PA) under normothermic and hypothermic (15 degrees C) conditions, using immunohistochemistry for light and electron microscopy. Neostriatal neurons of 6-month-old rats that were subjected to 19 and 20 min of PA, showed an increase of NF 200 kDa immunostaining mainly in the axon fascicles in comparison with the control and hypothermia groups. In contrast, no alterations were seen with NF68 and NF160 neurofilament antibodies. Furthermore, the same PA groups showed astroglial cells with enhanced GFAP immunoreactivity, evidencing a typical astroglial reaction with a clear hypertrophy of these cells. A quantitative image analysis confirmed these observations. Hypothermic treated animals did show neither astroglial nor neuronal cytoskeletal changes in comparison to the control group. These findings showed that PA produces chronic cytoskeletal alterations in the neostriatum cells that can be prevented by hypothermia.

Panic, suffocation false alarms, separation anxiety and endogenous opioids

This review paper presents an amplification of the suffocation false alarm theory (SFA) of spontaneous panic [Klein DF (1993). False suffocation alarms, spontaneous panics, and related conditions. An integrative hypothesis. Arch Gen Psychiatry; 50:306-17.]. SFA postulates the existence of an evolved physiologic suffocation alarm system that monitors information about potential suffocation. Panic attacks maladaptively occur when the alarm is erroneously triggered. That panic is distinct from Cannon's emergency fear response and Selye's General Alarm Syndrome is shown by the prominence of intense air hunger during these attacks. Further, panic sufferers have chronic sighing abnormalities outside of the acute attack. Another basic physiologic distinction between fear and panic is the counter-intuitive lack of hypothalamic-pituitary-adrenal (HPA) activation in panic. Understanding panic as provoked by indicators of potential suffocation, such as fluctuations in pCO(2) and brain lactate, as well as environmental circumstances fits the observed respiratory abnormalities. However, that sudden loss, bereavement and childhood separation anxiety are also antecedents of "spontaneous" panic requires an integrative explanation. Because of the opioid system's central regulatory role in both disordered breathing and separation distress, we detail the role of opioidergic dysfunction in decreasing the suffocation alarm threshold. We present results from our laboratory where the naloxone-lactate challenge in normals produces supportive evidence for the endorphinergic defect hypothesis in the form of a distress episode of specific tidal volume hyperventilation paralleling challenge-produced and clinical panic.

Postmortem cardiac troponin I and creatine kinase MB levels in the blood and pericardial fluid as markers of myocardial damage in medicolegal autopsy

The present study investigated cardiac troponin I (cTnI) and creatine kinase MB (CK-MB) in the blood and pericardial fluid from medicolegal autopsy cases (n=234, within 48h postmortem) with regard to the cause of death. The cTnI and CK-MB levels in cardiac, peripheral blood and pericardial fluid generally showed a mild and gradual postmortem time-dependent elevation (r=0.231-0.449, P<0.05-0.001). However, postmortem elevation of cTnI was larger for specific causes of death including acute myocardial infarction (AMI), cerebrovascular diseases (CVD), hyperthermia, fatal methamphetamine (MA) abuse and carbon monoxide (CO) intoxication and insignificant for recurrent myocardial infarction (RMI), chronic congestive heart diseases (CHD) and drowning, while that of CK-MB was greater for CO intoxication and insignificant for drowning. Cardiac blood and pericardial cTnI levels were relatively high for AMI, RMI, hyperthermia, MA abuse and CO intoxication, and was low for drowning. Elevated CK-MB level was observed for cardiac blood in asphyxiation and MA abuse cases and for peripheral blood in hyperthermia and MA abuse cases. When the cTnI/CK-MB ratio was estimated, it was independent of postmortem time, and the ratios for cardiac blood and pericardial fluid were significantly higher in cases of AMI, RMI, hyperthermia and CO intoxication but lower in cases of drowning. Elevations of cTnI levels in cardiac blood and pericardial fluid were related to the morphological severity of myocardial damage. These findings suggest that elevated cTnI and CK-MB levels in blood and pericardial fluid are related to ischemic, hypoxic and/or cytotoxic myocardial damage, which are characteristic of the cause of death, although the levels increase after death depending on myocardial damage at the time of death.

[Postmortem changes of liver phosphofructokinase-2 level in rats following different causes of death]

OBJECTIVE

To study the changes of liver phosphofructokinase-2 (PFK-2) level at different postmortem intervals as well as due to different causes of death.

METHODS

One hundred and five rats were randomly divided into 3 groups and the rats were sacrificed by either bleeding, suffocating, and neck breaking, respectively. The content of liver PFK-2 at 0, 1, 2, 4, 8, 12 and 24 hours following death were studied using immunohistochemishtry and image analysis.

RESULTS

PFK-2 content of the rat's liver in all 3 groups showed a linear decrease at different postmortem intervals with no significant statistical differences found between the different groups.

CONCLUSION

PFK-2 level in rat liver appears to decrease linearly in correlation with prolonged PMI.

[Comparison of the contents of ATP, ADP, and AMP in the cardiac muscle of rat killed by different manners]

OBJECTIVE

The content changes of energy substances in the cardiac muscle of rat killed by different manners were investigated to elucidate evidence that can be used to determine the modes of death and postmortem interval.

METHODS

One hundred and eighty rats were randomly allocated into 3 groups and killed by bleeding, suffocating, and neck breaking, respectively. The contents of ATP, ADP, and AMP in the cardiac muscle of rats killed by the different manners at different death intervals (0, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 18, and 24 h) were measured by HPLC.

RESULTS

There were significant differences observed in the contents of ATP and AMP in the rats' cardiac muscle in different groups at most of the intervals (P < 0.05) and at all of the intervals within the same group (P < 0.01), but no differences were found in the ADP contents in any of the group at most of the intervals.

CONCLUSION

The content changes of energy substances (ATP and AMP) in the cardiac muscle of dead rats may provide a basis for determination of the death manners and postmortem intervals.

[Induction of hypoxia-inducible factor-1alpha in two kinds of rats asphyxiation death models]

OBJECTIVE

To investigate the expression of hypoxia-inducible factor 1-alpha (HIF1-alpha) in the heart, lung, liver and kidney in rats died of two typical models of asphyxia.

METHODS

Two asphyxia models were made and tissue samples of the dead rats were collected from different groups at various postmortem duration. The expression and the changes of HIF1-alpha in various tissues were examined by immunohistochemistry and image analysis techniques. Results Significant expression of HIF1-alpha was observed in the myocardial fibers, kidney cells, liver cells and lung cells in both asphyxia models, but not in the control group. The expression of HIF1-alpha in various tissues in the rat died of nitrogen gas breathing was found in the nuclei at 0 hour and the expression level decreased gradually thereafter. The HIF1-alpha expression level and duration in various tissues of the rat died of hanging were higher and longer than that of the former group, with a peak of the expression level observed 6 hours after death, and then started to decline in all tissues except the heart where the expression still showed an increase 24 hours after death. The control groups showed a steady expression in the cytoplasm but not in the nuclei.

CONCLUSION

HIF1-alpha appears to be a valuable biomarker in the diagnosis of asphyxia within 24 hours after death.

[Correlation between matrix metalloproteinases activities and myocardial injury in neonatal rats after asphyxia]

OBJECTIVE

To study possible correlation between matrix metalloproteinases (MMPs) activities and myocardial injury after asphyxia in neonatal Wistar rats.

METHOD

Sixty neonatal Wistar rats (7 to 10 days old) were randomly divided into four groups: control group (group D); asphyxia groups A, B and C (1 day, 7 days, 14 days after asphyxia), every group had 15 rats. In the asphyxia groups, animal model was produced by normobaric asphyxia. Groups A, B and C were sacrificed on days 1, 7 and 14 days after asphyxia, and group D rats were sacrificed on the 7 th day. Then the heart blood was taken to tested the serum cTnI. The myocardial MMPs-3 and 9 activity was measured by using immunohistochemical assay. Histological sections of the hearts were stained with hematoxylin-eosin and myocardial histopathological scores were determined under an optical microscope. The amount of myocardial collagen was measured by means of chloramines T.

RESULTS

cTnI was significantly higher in group A (0.3680 +/- 0.40 ng/ml) than group D (0.0783 +/- 0.06 ng/ml) (P < 0.05), and was lower in group B (0.1889 +/- 0.15 ng/ml) but still significantly different from that of group D (P < 0.05), and declined to the normal level in group C (0.1338 +/- 0.07 ng/ml), but the difference between groups C and D was not significant (P > 0.05). Myocardial tissue MMPs-3 activity was transiently high in group A (0.1847 +/- 0.04), higher in group B (0.2780 +/- 0.05) as compared to group D (0.1213 +/- 0.03) (P < 0.05 for all). The activity of MMPs-3 increased earlier than that of MMPs-9. The amount of myocardial collagen of group B (38.94 +/- 0.67) and C (40.69 +/- 0.75) was significantly greater than that of group D (P < 0.05). Myoardial tissue MMPs-3 and MMPs-9 positively correlated with myocardial histopathological scores (r = 0.669, 0.667, P < 0.05) and myocardial collagen (r = 0.482, 0.679, P < 0.05).

CONCLUSIONS

In rats with asphyxia, there was an excess activation of myocardial MMPs-3 and MMPs-9 activities and secondary to which, the quantity of myocardial collagen increased. The injuries of myocardium may be closely associated with myocardial tissue MMPs. MMPs may be used to evaluate the severity of myocardial interstitial damage.

Melatonin reduces inflammation and cell death in white matter in the mid-gestation fetal sheep following umbilical cord occlusion

The premature infant is at increased risk of cerebral white matter injury. Melatonin is neuroprotective in adult models of focal cerebral ischemia and attenuates ibotenate-induced white matter cysts in neonatal mice. Clinically, melatonin has been used to treat sleep disorders in children without major side effects. The aim of this study was to investigate the protective and anti-inflammatory effects of melatonin in the immature brain following intrauterine asphyxia. Fetal sheep at 90 d of gestation were subjected to umbilical cord occlusion. Melatonin (20 mg/kg, n = 9) or vehicle (n = 10) was administered IV to the fetus, starting 10 min after the start of reperfusion and continued for 6 h. Melatonin treatment resulted in a slower recovery of fetal blood pressure following umbilical cord occlusion, but without changes in fetal heart rate, acid base status or mortality. The production of 8-isoprostanes following umbilical cord occlusion was attenuated and there was a reduction in the number of activated microglia cells and TUNEL-positive cells in melatonin treated fetuses, suggesting a protective effect of melatonin. In conclusion, this study shows that melatonin attenuates cell death in the fetal brain in association with a reduced inflammatory response in the blood and the brain following intrauterine asphyxia in mid-gestation fetal sheep.

Intestinal microcirculatory dysfunction during the development of experimental necrotizing enterocolitis

The aim of this study was to evaluate changes in intestinal microcirculation during necrotizing enterocolitis (NEC) and to examine the effect of endothelin (ET)-1 on the intestinal microcirculation. Prematurely born rats were either hand-fed formula (NEC) or dam fed (DF) and were exposed to asphyxia and cold stress twice daily to induce disease. At 0, 2, 3, and 4 d after the birth, the microcirculation in the ileum was examined using in vivo microscopic methods. The nutritive microvascular perfusion in the NEC group was progressively compromised from d 3 to d 4 (35% and 50% decrease, respectively) when compared with DF rats. Concomitantly, intestinal blood flow assessed by laser Doppler flowmetry was significantly reduced at d 2, 3, and 4 (by 31%, 36%, and 73%, respectively). Levels of ET-1 mRNA in the ileum were increased 3.7-fold. Microvascular responses to topically applied ET-1 were significantly increased in the NEC group, which was associated with decreased expression of ETB receptor. These results suggest that microcirculatory dysfunction in the distal ileum of neonatal rats with NEC contributes to disease progression and that enhanced microvascular responsiveness to ET-1 may participate in these microcirculatory disturbances.

Postmortem determination of concentrations of stress hormones in various body fluids--is there a dependency between adrenaline/noradrenaline quotient, cause of death and agony time?

To find out whether a certain cause of death or a certain length of an agonal period shows specific adrenaline or noradrenaline profiles, heart blood, femoral vein blood, liquor, urine and vitreous humour were taken from corpses (n = 98) at the Medical School Hannover, and noradrenaline and adrenaline were determined using high-performance liquid chromatography (HPLC). Corpses were classified according to the following five categories: short agony, long agony, state after hanging, state after asphyxiation and state after CPR with documented administration of epinephrine. Once results were collected the adrenaline/noradrenaline quotient was determined. It became clear that there were no significant differences regarding the concentration of adrenaline and noradrenaline in the various body fluids in relation to the above-mentioned categories. The means adrenaline/noradrenaline quotients in femoral vein blood were 0.21 +/- 0.29 for hanged persons, 0.38 +/- 0.47 for asphyxiated persons, 0.17 +/- 0.19 for those with short agony and 0.42 +/- 0.43 for those with long agony, significantly below 1 (p < 0.001; p = 0.001; p = 0.003). For condition after CPR we found an adrenaline/noradrenaline quotient of 2.81 +/- 5.8. In liquor the adrenaline/noradrenaline quotients for short agony was 0.17 +/- 0.17, for hanged persons 0.18 +/- 0.19 and for asphyxiated ones 0.30 +/- 0.38, significantly lower than 1 (p < 0.001). In urine the adrenaline/noradrenaline quotients for all categories are lower than 1 (p < 0.001); short agony (0.13 +/- 0.09), long agony (0.21 +/- 0.16), hanged (0.15 +/- 0.16), asphyxiated (0.14 +/- 0.08) and CPR (0.14 +/- 0.06). In vitreous humour the quotients for short agony (0.14 +/- 0.28), long agony (0.13 +/- 0.12), hanged (0.07 +/- 0.09) and asphyxiated (0.09 +/- 0.11) are lower than 1 (p < 0.001). The spread of data for the adrenaline/noradrenaline quotient did not allow for any conclusions about cause of death and length of agony in individual cases.

Differences in postmortem urea nitrogen, creatinine and uric acid levels between blood and pericardial fluid in acute death

Previous studies showed significant differences in postmortem urea nitrogen (UN), creatinine (Cr) and uric acid (UA) levels in heart blood depending on the causes of death, including acute death. In addition, the levels in pericardial fluid approximated the clinical serum reference ranges, and their elevations may be assessed based on clinical criteria. The present study investigated difference between blood and pericardial levels of these markers. Medicolegal autopsy cases (n=556, within 48h postmortem) of the following causes of death were examined: injury (n=136), asphyxiation (n=50), drowning (n=39), fire fatalities (n=99), hyperthermia (n=11), hypothermia (n=8), poisoning (n=26), delayed traumatic death (n=44) and natural diseases (n=143). When serum UN, Cr and UA levels were compared with the pericardial levels, there was an equivalency for delayed traumatic death and chronic renal failure, although each level was markedly elevated. Parallel increases in serum and pericardial UA and/or Cr levels were also observed for hypothermia and gastrointestinal bleeding. However, in drowning cases, the left cardiac and pericardial UN levels were lower than the right cardiac and peripheral levels, suggesting the influence of water aspiration. Significant elevations in serum and pericardial Cr and UA levels with a higher serum/pericardial UA ratio for fatal methamphetamine intoxication suggest progressive skeletal muscle damage due to advanced hypoxia/acidosis. Similar findings were often observed for other acute and subacute deaths. These findings suggest that a comparison between blood and pericardial nitrogenous compounds would be useful for investigating the cause and process of death.

Effects of CO2/HCO3− in Perilymph on the Endocochlear Potential in Guinea Pigs

The effect of CO(2)/HCO(3)(-) on the endocochlear potential (EP) was examined by using both ion-selective and conventional microelectrodes and the endolymphatic or perilymphatic perfusion technique. The main findings were as follows: (i) A decrease in the EP from approximately +75 to approximately +35 mV was produced by perilymphatic perfusion with CO(2)/HCO(3)(-)-free solution, which decrease was accompanied by an increase in the endolymphatic pH (DeltapH(e), approximately 0.4). (ii) Perilymphatic perfusion with a solution containing 20 mM NH(4)Cl produced a decrease in the EP (DeltaEP, approximately 20 mV) with an increase in the pH(e) (DeltapH(e), approximately 0.2), whereas switching the perfusion solution from the NH(4)Cl solution to a 5% CO(2)/25 mM HCO(3)(-) solution produced a gradual increase in the EP to the control level with the concomitant recovery of the pH(e). (iii) The perfusion with a solution of high or low HCO(3)(-) with a constant CO(2) level within 10 min produced no significant changes in the EP. (iv) Perfusion of the perilymph with 10 microg/ml nifedipine suppressed the transient asphyxia-induced decrease in EP slightly, but not significantly. (v) By contrast, the administration of 1 microg/ml nifedipine via the endolymph inhibited significantly the reduction in the EP induced by transient asphyxia or perilymphatic perfusion with CO(2)/HCO(3)(-)-free or 20 mM NH(4)Cl solution. These findings suggest that the effect of CO(2) removal from perilymphatic perfusion solution on the EP may be mediated by an increase in cytosolic Ca(2+) concentration induced by an elevation of cytosolic pH in endolymphatic surface cells.

[Expression of HIF1-alpha on myocardium and lung in rats model of asphyxia death]

OBJECTIVE

To investigate the expression of HIF1-alpha in heart and lung tissue died from asphyxia.

METHODS

The rats model of asphyxia death was constructed by hanging, different asphyxia groups and control group sets were made according the postmortem time (0,2,6,24 h), immunohistochemistry and half-quantitative RT-PCR methods were used to investigate expression of HIF1-alpha and mRNA changes on heart and lung tissue.

RESULTS

The positive staining of HIF1-alpha could be observed in the myocardium and lung tissue. Significant differences were found between the groups of asphyxia and their corresponding control group. HIF1-alpha expression was found in all the asphyxia groups while it was only expressed in the control groups of 2 h, 6 h and 24 h. Nucleic positive staining could be detected in all the asphyxia groups but none was found in the control groups. RT-PCR showed that the expression of mRNA between 0 h asphyxia group and 0 h control group were equal in both cardic muscle and lung, but elevated expression in groups of 2,6,24h compared to their control groups.

CONCLUSION

The nuclear positive staining of HIF1-alpha in heart and lung can be a special character of suffocation death.

Stress-induced behaviour in adult and old rats: effects of neonatal asphyxia, body temperature and chelation of iron

Perinatal asphyxia in mammals leads to iron accumulation in the brain, which results in delayed neurobehavioural disturbances, including impaired learning and abnormal alertness over their entire life span. The aim of this investigation was to verify our hypothesis that newborn rats, showing reduced normal body temperature, are protected against neurotoxicity of the asphyxia up to senescence. Alertness was studied in adult and old male Wistar rats after exposure to critical neonatal anoxia: (i) at physiological neonatal body temperature of 33 degrees C, (ii) at body temperature elevated to 37 degrees C, or (iii) at body temperature elevated to 39 degrees C (the thermal conditions remained unchanged both during anoxia and for 2 h postanoxia). To elucidate the effect of iron-dependent postanoxic oxidative damage to the brain, half of the group (iii) was injected with deferoxamine, a chelator of iron. Postanoxic behavioural disturbances were recorded in open-field, elevated plus-maze, and sudden silence tests when the rats reached the age of 12 and 24 months. Open-field stress-induced motor activity was reduced in rats subjected to neonatal anoxia under hyperthermic conditions. In contrast, these rats were hyperactive in the plus-maze test. Both the plus-maze and sudden silence tests show reduced alertness of these rats to external stimuli signalling potential dangers. The behavioural disturbances were prevented by body temperature of 33 degrees C and by administration of deferoxamine.

Nicotinamide prevents the effect of perinatal asphyxia on dopamine release evaluated with in vivo microdialysis 3 months after birth

The present study shows that nicotinamide prevents the long-term effect of perinatal asphyxia on dopamine release monitored with in vivo microdialysis in the neostriatum of 3-month-old rats. Perinatal asphyxia was induced by immersing foetuses-containing uterine horns removed from ready-to-deliver rats into a water bath for 16 or 20 min. Sibling, spontaneous, and caesarean-delivered pups were used as controls. Saline or nicotinamide (0.8 mmol/kg, i.p.) was administered to control and asphyxia-exposed animals 24, 48, and 72 h after birth. After weaning, the rats were randomly distributed in laboratory cages for animal care under standard ad libitum laboratory conditions. Approximately 3 months after birth, control and asphyxia-exposed animals were implanted with microdialysis probes into the lateral neostriatum for measuring extracellular monoamine and metabolite levels with HPLC-coupled to an electrochemical detection system under basal, D-amphetamine, and K(+)-depolarising conditions. There was an asphyxia-dependent decrease of extracellular dopamine levels, mainly observed during the periods when D-amphetamine (100 microM) or KCl (100 mM) was added into the perfusion medium. Compared to that observed in caesarean-delivered controls, the effect of D-amphetamine on dopamine levels was decreased by approximately 30 and 70% in animals exposed to 16 and 20 min of perinatal asphyxia, respectively. The effect of K(+)-depolarisation was decreased by 45 and 83% in animals exposed to the same periods of asphyxia, respectively. Both effects were prevented by nicotinamide, even if the treatment started 24 h after the insult. The present results support the idea of nicotinamide as an interesting molecule, useful for protecting against anoxia/ischemia occurring at neonatal stages. Nicotinamide can help to restore NADH/NAD+ depletion, but also to inhibit PARP-1 overactivation, a mechanism of action that has attracted attention, representing a novel target for neuroprotection following insults involving energy failure.

The roles of bacteria and TLR4 in rat and murine models of necrotizing enterocolitis

Bacteria are thought to contribute to the pathogenesis of necrotizing enterocolitis (NEC), but it is unknown whether their interaction with the epithelium can participate in the initiation of mucosal injury or they can act only following translocation across a damaged intestinal barrier. Our aims were to determine whether bacteria and intestinal epithelial TLR4 play roles in a well-established neonatal rat model and a novel neonatal murine model of NEC. Neonatal rats, C57BL/6J, C3HeB/FeJ (TLR4 wild type), and C3H/HeJ (TLR4 mutant) mice were delivered by Cesarean section and were subjected to formula feeding and cold asphyxia stress or were delivered naturally and were mother-fed. NEC incidence was evaluated by histological scoring, and gene expression was quantified using quantitative real-time PCR from cDNA generated from intestinal total RNA or from RNA obtained by laser capture microdissection. Spontaneous feeding catheter colonization or supplementation of cultured bacterial isolates to formula increased the incidence of experimental NEC. During the first 72 h of life, i.e., the time frame of NEC development in this model, intestinal TLR4 mRNA gradually decreases in mother-fed but increases in formula feeding and cold asphyxia stress, correlating with induced inducible NO synthase. TLR4, inducible NO synthase, and inflammatory cytokine induction occurred in the intestinal epithelium but not in the submucosa. NEC incidence was diminished in C3H/HeJ mice, compared with C3HeB/FeJ mice. In summary, bacteria and TLR4 play significant roles in experimental NEC, likely via an interaction of intraluminal bacteria and aberrantly overexpressed TLR4 in enterocytes.

Quantitative RT-PCR assays of hypoxia-inducible factor‐1α, erythropoietin and vascular endothelial growth factor mRNA transcripts in the kidneys with regard to the cause of death in medicolegal autopsy

Accumulating studies demonstrate that the expressions of hypoxia-inducible factor 1 (HIF-1), erythropoietin (EPO) and vascular endothelial growth factor (VEGF) depend on cellular oxygen tension, which is involved in the pathological process of tissue hypoxia and/or ischemia. The present study investigated hypoxia-inducible factor-1alpha (HIF-1alpha), EPO and VEGF mRNA expressions in the kidney with regard to the cause of death in medicolegal autopsy. Relative quantifications of HIF-1alpha, EPO and VEGF mRNAs, based on real-time TaqMan reverse transcription-polymerase chain reaction (RT-PCR), were performed on tissue specimens obtained from consistent sites of the bilateral renal cortices. The cases (total, n=245, 6-48h postmortem) included fatal blunt/sharp instrument injuries (n=53/31), asphyxia (n=28: aspiration, n=8; strangulation/hanging, n=20), drowning (n=27), fire fatality (n=62), acute myocardial infarction/ischemia (AMI, n=39), and gastrointestinal hemorrhage (n=5). Both HIF-1alpha and EPO mRNA levels were significantly lower in drowning cases. More characteristic findings were found for VEGF mRNA: it showed higher expression levels for AMI, acute blunt/sharp instrument injury, and aspiration, whereas it was lower for neck compression (strangulation/hanging), drowning, fire fatality with higher blood carboxyhemoglobin (COHb) levels (>60%), peracute blunt injury, and gastrointestinal hemorrhage. Quantitative assays of renal HIF-1alpha, EPO and VEGF mRNA transcripts are potentially useful for investigating the pathophysiology of death, and VEGF mRNA may be especially useful as an indication of acute circulatory failure.

Asphyxia and depolarization increase adenosine levels in perilymph

Extracellular adenosine has been suggested as a modulator of cochlear function. To date the release of adenosine into the extracellular spaces of the cochlea has not been demonstrated. Therefore, experiments were designed to examine whether adenosine release into perilymph could be detected in response to depolarization by high potassium concentrations or in response to asphyxia. For this purpose, the perilymph compartment of guinea pigs was perfused with an artificial perilymph and the effluent assayed for ATP, ADP, AMP and adenosine. Results indicate that potassium induced a slight, significant increase and asphyxia induced a very large, significant increase in adenosine levels in perilymph effluent. No changes in the levels of the other compounds were measured. It is concluded that depolarization and asphyxia can induce the release of adenosine into perilymph.

Postmortem cardiac troponin T levels in the blood and pericardial fluid. Part 2: Analysis for application in the diagnosis of sudden cardiac death with regard to pathology

Although previous forensic pathological studies have suggested the possible application of cardiac troponins in the diagnosis of myocardial infarction, there appears to be insufficient data with regard to its cardiac pathology. The present study analyzed the heart blood, peripheral blood and pericardial fluid levels of cardiac troponin T (cTnT) in sudden cardiac deaths (n = 96) within 48h postmortem in relation to pathological findings of acute myocardial infarction (AMI, n = 34), recurrent myocardial infarction (RMI, n = 23), ischemic heart disease without any pathological evidence of infarction (IHD, n = 24) and other heart diseases (OHD, n = 15). Control groups (n = 75, survival time <24 h) within 48 h postmortem consisted of asphyxiation (n = 35), drowning (n = 27) and cerebrovascular diseases (n = 13). There was a marked correlation in the cTnT levels between right and left heart blood samples. The pericardial level was usually higher than either heart blood level, and the external iliac venous blood level was the lowest. Although postmortem time-dependent increases in heart and pericardial blood cTnT levels were observed in most groups, they were most evident for AMI and asphyxiation. In the early postmortem period (<12 h) there was no significant difference between AMI or RMI and the other groups except for drowning. After 12 h postmortem, significantly elevated heart blood and pericardial cTnT levels were observed for AMI and RMI showing multiple interstitial hemorrhages and necrosis compared to those with localized eosinophilic changes or patchy interstitial hemorrhages, IHD and OHD. These differences were the smallest for peripheral blood. For sudden cardiac death cases, the difference in cTnT level at each site among the causes of death was independent of gender, age, heart or lung weight and pathologies of affected coronary artery and severity of coronary stenosis. These observations suggest that the elevation in postmortem blood and pericardial cTnT levels in sudden cardiac death may depend on the severity of ischemic myocardial damage including the size and intensity of myocardial lesions involving multiple interstitial hemorrhages and necrosis, and also the postmortem period for heart and pericardial levels.

Immunohistochemical distribution of S-100 protein in the cerebral cortex with regard to the cause of death in forensic autopsy

S-100 protein (S100) is an acidic calcium-binding protein, which is abundantly found in the brain. The aim of the present study was to investigate the immunohistochemical distribution of S100 in the cerebral cortex in forensic autopsy cases with regard to the cause of death and relationship to its serum levels. The cases (n = 286, 3-48 h postmortem) included fatal head injuries (n = 89), acute death from other blunt injuries (n = 29), sharp instrument injuries (n = 20), asphyxiation (n = 29: strangulation/hanging, n = 22; aspiration, n = 7), drownings (n = 22), fire fatalities (n = 68), cerebrovascular diseases (n = 9) and acute myocardial infarction/ischemia (AMI, n = 20). S100-immunopositivity was mainly observed in the gliacytes, in part, in the neurons and myelins. For S100B-immunostaining, the gliacytes and myelins were positive, whereas the neurons were negative. Positivity in astrocytes was dependent on the cause of death, and was significantly lower in acute deaths due to strangulation/hanging and drowning, and mildly low in those due to injuries. Positivity in neurons and myelins was frequently observed in delayed head injury deaths and fire fatalities, showing an inverse relationship with the positivity in astrocytes in head injury cases. For cases of acute death, there was an inverse relationship between S100-positivity in the astrocytes and the serum S100B level. These observations suggest that astrocytes are more rapidly and severely injured than neurons during fatal brain damage, thereby causing an elevation in the serum S100B level.

Gene response of mouse skin to pressure injury in the neck region

We analyzed the gene expression pattern in mouse skin following compression of the neck by fluorescent mRNA differential display (FDD-PCR). RNA was isolated from the skin tissue immediately or 30 min after ligation at the neck for 25 min resulting in death (Group A-0, Group A-30). Control mice underwent no compression of the neck and were killed by decapitation (Group C-0, Group C-30). FDD-PCR and sequence analysis revealed that the faciogenital dysplasia gene (Rho member families) and secreted frizzled related protein 1 (modulator of Wnt networks) were enhanced only in the Group A-30. In addition, common salivary protein 1 and mouse 0 day neonate skin cDNA clone z4631433E12 from the RIKEN full-length enriched library were also induced in Groups A-0 and A-30. These findings were consistent with the results of statistical analysis by ANOVA following quantitative real-time PCR. No differences in band pattern were observed between Group C-0 and Group C-30. Therefore, our findings suggested that the altered expression of genes was associated with signal transduction. The results may contribute to clarifying the pathophysiology of compression of the skin and may be useful in the diagnosis of suffocation.

Postmortem cardiac troponin T levels in the blood and pericardial fluid. Part 1. Analysis with special regard to traumatic causes of death

In forensic pathology, previous studies have suggested the possible application of cardiac troponins in the diagnosis of myocardial infarction. However, there appears to be insufficient practical data on other causes of death. The present study was a comprehensive analysis of the cardiac, peripheral blood and pericardial levels of cardiac troponin T (cTnT) in serial medicolegal autopsy cases (n = 405) with a survival time <24 h and within 48 h postmortem to assess the validity of investigating myocardial damage with special regard to traumatic causes of death. These included blunt and sharp instrument injury (n = 122 and 21, respectively), asphyxiation (n = 35), drowning (n = 27), fire fatalities (n = 94), hyperthermia (n = 13), hypothermia (n = 6), fatal methamphetamine (MA) abuse (n = 12) and carbon monoxide (CO) poisoning (n = 5) in comparison with myocardial infarction (MI, n = 57) and cerebrovascular diseases (n = 13). Cases within 12h postmortem usually showed lower cardiac and pericardial cTnT levels than did those of longer postmortem time of 12-48 h. In the early postmortem period of <12 h, significantly elevated serum cTnT levels were observed for hyperthermia. Thereafter, fatal MA abuse, CO poisoning and MI cases also showed higher levels. However, cTnT remained at lower levels for hypothermia and drowning. The elevation of cTnT was associated with the pathology of advanced myocardial damage involving swelling and liquefactive necrosis. The above-mentioned differences were the smallest for peripheral blood. These findings suggest that elevations in postmortem serum and pericardial cTnT levels depend on the severity of myocardial damage at the time of death and are related to the pathological findings, although postmortem interference should be taken into consideration.

Suffocation and respiratory responses to carbon dioxide and breath holding challenges in individuals with panic disorder

OBJECTIVE

Findings showing that individuals with panic disorder (PD) are prone to experience panic attacks when inhaling CO2-enriched air have given rise to the hypothesis that physiological systems underlying the experience of suffocation may be important in the etiology of PD. In this study, we tested several predictions stemming from this view.

METHODS

Forty individuals with PD and 32 controls underwent both a breath-holding challenge and a CO2 rebreathing challenge. A wide array of physiological and psychological responses, including continuous measurements of subjective suffocation, was recorded.

RESULTS

Individuals with PD experienced elevated physiological reactivity to both challenges and greater levels of suffocation sensations during the rebreathing challenge. Furthermore, PD individuals who experienced a panic attack in response to the rebreathing challenge exhibited faster but shallower breathing during the challenge than did other PD individuals.

CONCLUSION

Findings are consistent with theories linking PD to hypersensitive brain systems underlying the experience of suffocation. The possibility that subjective suffocation was in part mediated by peripheral interoceptive disturbances (vs. brainstem dysregulation) is discussed.

Stress in pregnancy activates neurosteroid production in the fetal brain

Neurosteroids such as allopregnanolone are potent agonists at the GABA(A) receptor and suppress the fetal CNS activity. These steroids are synthesized in the fetal brain either from cholesterol or from circulating precursors derived from the placenta. The concentrations of allopregnanolone are remarkably high in the fetal brain and rise further in response to acute hypoxic stress, induced by constriction of the umbilical cord. This response may result from the increased 5alpha-reductase and cytochrome P-450(SCC) expression in the brain. These observations suggest that the rise in neurosteroid concentrations in response to acute hypoxia may represent an endogenous protective mechanism that reduces excitotoxicity following hypoxic stress in the developing brain. In contrast to acute stress, chronic hypoxemia induces neurosteroidogenic enzyme expression without an increase in neurosteroid concentrations and, therefore, may pose a greater risk to the fetus. At birth, the allopregnanolone concentrations in the brain fall markedly, probably due to the loss of placental precursors; however, stressors, including hypoxia and endotoxin-induced inflammation, raise allopregnanolone concentrations in the newborn brain. This may protect the newborn brain from hypoxia-induced damage. However, the rise in allopregnanolone concentrations was also associated with increased sleep. This rise in sedative steroid levels may depress arousal and contribute to the risk of sudden infant death syndrome. Our recent findings indicate that acute hypoxic stress in pregnancy initiates a neurosteroid response that may protect the fetal brain from hypoxia-induced cell death, whereas the decline in allopregnanolone levels after birth may result in greater vulnerability to brain injury in neonates.

Transient NMDA receptor-mediated hypoperfusion following umbilical cord occlusion in preterm fetal sheep

Exposure to severe hypoxia leads to delayed cerebral and peripheral hypoperfusion. There is evidence in the very immature brain that transient abnormal glutaminergic receptor activity can occur during this phase of recovery. We therefore examined the role of N-methyl-D-aspartate (NMDA) receptor activity in mediating secondary hypoperfusion in preterm fetal sheep at 70% of gestation. Fetuses received either sham asphyxia or asphyxia and were studied for 12 h recovery. The specific, non-competitive NMDA receptor antagonist dizocilpine maleate (2 mg kg-1 bolus plus 0.07 mg kg h-1i.v.) or saline (vehicle) was infused from 15 min after asphyxia until 4 h. In the asphyxia-vehicle group abnormal epileptiform EEG transients were observed during the first 4 h of reperfusion, the peak of which corresponded approximately to the nadir in peripheral and cerebral hypoperfusion. Dizocilpine significantly suppressed this activity (2.7+/-1.3 versus 11.2+/-2.7 counts min-1 at peak frequency, P<0.05) and markedly delayed and attenuated the rise in vascular resistance in both peripheral and cerebral vascular beds observed after asphyxia, effectively preventing the initial deep period of hypoperfusion in carotid blood flow and femoral blood flow (P<0.01). However, while continued infusion did attenuate subsequent transient tachycardia, it did not prevent the development of a secondary phase of persistent but less profound hypoperfusion. In conclusion, the present studies suggest that in the immature brain the initial phase of delayed cerebral and peripheral hypoperfusion following exposure to severe hypoxia is mediated by NMDA receptor activity. The timing of this effect in the cerebral circulation corresponds closely to abnormal EEG activity, suggesting a pathological glutaminergic activation that we speculate is related to evolving brain injury.