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.

Xenon provides short-term neuroprotection in neonatal rats when administered after hypoxia-ischemia

BACKGROUND AND PURPOSE

Brain injury after hypoxic-ischemic insults evolves via an apoptotic/necrotic cascade. Glutamate over release and N-methyl-d-aspartate (NMDA) receptor over activation (excitotoxicity) are believed to trigger this process. Xenon is a nontoxic anesthetic gas that reduces neurotransmitter release and functionally antagonizes NMDA receptors. Administering xenon to hypoxic-ischemic newborns might be clinically effective if the neurotoxic processes continue evolving after delivery. We sought to determine whether xenon administration after the initial hypoxic-ischemic insult was neuroprotective.

METHODS

Fifty 7-day-old rats received a 90-minute hypoxic insult after unilateral carotid ligation. They were then randomized to breathe 1 of 2 gas mixtures for 3 hours: 50% Xe/30% O2/20% N2 or 30% O2/70% N2.

RESULTS

One week after hypoxic-ischemic survival, significant global protection was seen in the xenon group (80% less injury); cortex/white matter (88% versus 25%), hippocampus (62% versus 0%), basal ganglia (81% versus 25%), and thalamus (50% versus 0%; percentage of global damage score in nonxenon versus xenon groups, respectively).

CONCLUSIONS

Three hours of xenon administration commenced after hypoxia-ischemia in neonatal rats provides short-term neuroprotection. This finding suggests that treatment with xenon after perinatal asphyxia would also be neuroprotective. Because xenon does not cause other neurotoxic effects and has demonstrated minimal side effects in extensive anesthesia studies, it would make an ideal candidate for the treatment after human perinatal hypoxia-ischemia.

Xenon preconditioning reduces brain damage from neonatal asphyxia in rats

Xenon attenuates on-going neuronal injury in both in vitro and in vivo models of hypoxic-ischaemic injury when administered during and after the insult. In the present study, we sought to investigate whether the neuroprotective efficacy of xenon can be observed when administered before an insult, referred to as 'preconditioning'. In a neuronal-glial cell coculture, preexposure to xenon for 2 h caused a concentration-dependent reduction of lactate dehydrogenase release from cells deprived of oxygen and glucose 24 h later; xenon's preconditioning effect was abolished by cycloheximide, a protein synthesis inhibitor. Preconditioning with xenon decreased propidium iodide staining in a hippocampal slice culture model subjected to oxygen and glucose deprivation. In an in vivo model of neonatal asphyxia involving hypoxic-ischaemic injury to 7-day-old rats, preconditioning with xenon reduced infarction size when assessed 7 days after injury. Furthermore, a sustained improvement in neurologic function was also evident 30 days after injury. Phosphorylated cAMP (cyclic adenosine 3',5'-monophosphate)-response element binding protein (pCREB) was increased by xenon exposure. Also, the prosurvival proteins Bcl-2 and brain-derived neurotrophic factor were upregulated by xenon treatment. These studies provide evidence for xenon's preconditioning effect, which might be caused by a pCREB-regulated synthesis of proteins that promote survival against neuronal injury.

Cerebral histologic and electrocorticographic changes after asphyxia in fetal sheep

Asphyxia can cause neurologic damage in the fetus, but there are few data relating severity or duration of asphyxia to the degree of cerebral damage. We report cerebral histologic and electrophysiologic changes after asphyxia in chronically instrumented late-gestation fetal sheep. We reduced uterine blood flow to produce an ascending aortic blood oxygen content less than 1.5 mM for either 30 or 60 min (n = 13). In a subsequent protocol (n = 6), if full occlusion of the common uterine artery for 15 min did not reduce the EEG voltage to less than 20% of baseline, supplementary maternal hypoxia was added for a maximum of 120 min. Histologic outcome was assessed 3 d postinsult. Uterine artery occlusion resulted in severe hypoxemia, hypercarbia, acidosis, and an initial hypertension and bradycardia. Eight of 14 surviving fetuses showed neuronal damage, with greatest loss in the parasagittal cortex, striatum, and the CA1/2 region of the hippocampus. Neuronal damage was strongly associated with the percentage of decrease in blood pressure during the insult (r = 0.75, p less than 0.005) but not with the degree of hypoxia. No other factor was independently predictive, but, when considered separately, pH (r = 0.54; p less than 0.05) and loss of intensity of the EEG (r = 0.61, p less than 0.02) at the end of asphyxia were also correlated with outcome. The pH fell to less than 7.0 in six of eight fetuses with damage, whereas it remained greater than 7.0 in five of six without damage (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Transient umbilical cord occlusion causes hippocampal damage in the fetal sheep

OBJECTIVE

The purpose of our study was to examine the neuronal outcome after a standardized period of umbilical cord occlusion.

STUDY DESIGN

The umbilical cord was clamped for 10 minutes in nine experimental and four control chronically instrumented fetal sheep. Three days later the animals were killed for histologic interpretation. Systemic, electrophysiologic, and neurohistologic effects were compared by analysis of variance.

RESULTS

Clamping of the cord resulted in transient severe asphyxia, hypotension (24 +/- 5 mm Hg, p < 0.01), bradycardia (72 +/- 14 beats/min, p < 0.001), depressed electroencephalographic activity (-17 +/- 2 dB, p < 0.001), and an increase in cortical impedance. The electroencephalographic activity was depressed for 5 +/- 2 hours in spite of rapid recovery of arterial oxygen content. Neuronal loss was found in the hippocampus. Neither epileptiform electroencephalographic activity nor infarction were observed. Three animals with poor blood gas levels died during the occlusion.

CONCLUSION

An isolated and brief period of umbilical cord occlusion in utero can cause predominantly hippocampal damage without persistent functional changes in cortical activity and with rapid recovery of other potential indicators of fetal asphyxia.

Central nervous system findings in the newborn monkey following severe in utero partial asphyxia

Seizures, brain swelling, and cortical necrosis have been observed in the newborn rhesus monkey following a 2 to 4-hour period of intrauterine partial asphyxia produced by halothane-induced maternal hypotension. These clinical and neuropathologic findings are similar to those seen in human newborn infants who have experienced an episode of intrauterine asphyxia from such a cause as premature placental separation. The present study strongly indicates that fetal partial asphyxia, from any cause, in the absence of fetal circulatory collapse or fetal head compression, may be the primary event that sets in motion a vicious cycle of brain swelling and impaired cerebral blood flow, leading finally to cerebral necrosis.

Lung immunopathology in cases of sudden asthma death

The histopathology of airway inflammation in rare cases of sudden asphyxic asthma death (SAAD) is unclear. This study examines, for the first time, the relative disposition of lymphocyte and macrophage subsets and eosinophils in proximal and distal tissues of such cases. Multiple resection specimens from five cases of SAAD were studied. Tissue blocks were obtained at necroscopy and immediately frozen in liquid nitrogen within 18 hours of death (death occurring within 1 h of the onset of an unprovoked asphyxic asthma attack). After immunohistological staining, frozen sections underwent semi-quantitative analysis (cell counts per unit area) for T-cells, macrophages and eosinophils using computerized imaging systems. Subsets of T-cells and macrophages were estimated using double immunofluorescence techniques. Variability within samples, between samples and between cases was compared. These cases of fatal asthma showed infiltrates of T-cells, macrophages and eosinophils within peribronchial tissues. Distinct from stable asthma, a CD8+ T-cell dominance was found. A high proportion of eosinophils were activated (EG2+), whereas the relative proportion of antigen-presenting cells (RFD1+) did not seem to be abnormal, although numbers of these cells were high. These features were seen both in proximal and distal tissues. The variability of these parameters within an individual was 9.4-15.2%, however, the variability between individual cases was greater. Sudden asphyxic asthma is associated with inflammatory infiltrates both of proximal and distal lung tissues. In contrast to stable asthma, this infiltrate contains large numbers of CD8+ T-cells, suggesting distinct qualitative as well as quantitative characteristics in the immunopathology of sudden asthma death.

Oleoresin capsicum (pepper) spray and "in-custody deaths"

Increasing use of oleoresin capsicum (OC) spray devices (i.e., pepper spray, pepper mace, OC, capsaicin) by law enforcement agencies as a means of sublethal force to control suspects has brought into question whether exposure to this noxious irritant (capsaicin) can cause or contribute to unexpected in-custody deaths. Capsaicin stimulates nociceptors in exposed mucous membranes to produce intense pain, particularly involving the conjunctiva, and generates systemic physiologic and behavioral responses consonant with such extreme discomfort. We describe two cases of in-custody death, both associated temporally with the use of pepper spray, to illustrate salient investigative considerations. As with any other in-custody death, a thorough autopsy and toxicologic analysis, coupled with evaluation of the premortem chain of events, postexposure symptomatology, and the extent of natural disease processes, will help to reveal the role of oleoresin capsicum spray as unrelated, contributory, or causative.

Positional asphyxia during law enforcement transport

Three cases of positional asphyxia are described that occurred while victims were in a prone position in rear compartments of police patrol cars. These deaths are attributed to positional asphyxia. Autopsy findings and specific scene and circumstantial correlations of the investigation are discussed with emphasis placed on the limitations of interpretation of the anatomic changes at autopsy.

Fetal heart rate variability and brain stem injury after asphyxia in preterm fetal sheep

This study was undertaken to determine the mechanisms mediating changes in fetal heart rate variability (FHRV) during and after exposure to asphyxia in the premature fetus. Preterm fetal sheep at 0.6 of gestation (91 ± 1 days, term is 147 days) were exposed to either sham occlusion ( n = 10) or to complete umbilical cord occlusion for either 20 ( n = 7) or 30 min ( n = 10). Cord occlusion led to a transient increase in FHRV with abrupt body movements that resolved after 5 min. In the 30 min group there was a marked increase in FHRV in the final 10 min of occlusion related to abnormal atrial activity. After reperfusion, FHRV in both study groups was initially suppressed and progressively increased to baseline levels over the first 4 h of recovery. In the 20 min group this improvement was associated with return of normal EEG activity and movements. In contrast, in the 30 min group the EEG was abnormal with epileptiform activity superimposed on a suppressed background, which was associated with abnormal fetal movements. As the epileptiform activity resolved, FHRV fell and became suppressed for the remainder of the study. Histological assessment after 72 h demonstrated severe brain stem injury in the 30 min group but not in the 20 min group. In conclusion, during early recovery from asphyxia, epileptiform activity and associated abnormal fetal movements related to evolving neural injury can cause a confounding transient increase in FHRV, which mimics the normal pattern of recovery. However, chronic suppression of FHRV was a strong predictor of severe brain stem injury.

Key neuroprotective role for endogenous adenosine A1 receptor activation during asphyxia in the fetal sheep

BACKGROUND AND PURPOSE

The fetus is well known to be able to survive prolonged exposure to asphyxia with minimal injury compared with older animals. We and others have observed a rapid suppression of EEG intensity with the onset of asphyxia, suggesting active inhibition that may be a major neuroprotective adaptation to asphyxia. Adenosine is a key regulator of cerebral metabolism in the fetus.

METHODS

We therefore tested the hypothesis that infusion of the specific adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), given before 10 minutes of profound asphyxia in near-term fetal sheep, would prevent neural inhibition and lead to increased brain damage.

RESULTS

DPCPX treatment was associated with a transient rise and delayed fall in EEG activity in response to cord occlusion (n=8) in contrast with a rapid and sustained suppression of EEG activity in controls (n=8). DPCPX was also associated with an earlier and greater increase in cortical impedance, reflecting earlier onset of primary cytotoxic edema, and a significantly smaller reduction in calculated cortical heat production after the start of cord occlusion. After reperfusion, DPCPX-treated fetuses but not controls developed delayed onset of seizures, which continued for 24 hours, and sustained greater selective hippocampal, striatal, and parasagittal neuronal loss after 72-hour recovery.

CONCLUSIONS

These data support the hypothesis that endogenous activation of the adenosine A1 receptor during severe asphyxia mediates the initial suppression of neural activity and is an important mechanism that protects the fetal brain.

Physiologic and histologic changes in near-term fetal lambs exposed to asphyxia by partial umbilical cord occlusion

OBJECTIVES

Our purpose was to characterize the histologic changes in the asphyxiated fetal lamb brain and to correlate the severity of these changes with fetal physiologic parameters during and after asphyxia.

STUDY DESIGN

Seventeen near-term fetuses were used for analysis: control group without manipulation (n = 4, 132 +/- 1.1 days of gestation at autopsy, mean +/- SEM), sham-asphyxia control group (n = 3, 132 +/- 1.3 days), and asphyxiated group, which successfully survived 72 hours after asphyxia (n = 10, 130 +/- 1.0 days). Asphyxia was produced by umbilical cord occlusion lasting for approximately 60 minutes until fetal arterial pH diminished to < 6.9 and base excess to < -20 mEq/L. Fetal heart rate, blood pressure, and electrocorticographic activity were continuously monitored. The fetuses were killed 72 hours after asphyxia, and the brains were fixed in formalin and processed for histologic and immunocytochemical studies.

RESULTS

Neuropathologic changes varied from case to case, ranging from almost total infarction of cortical and subcortical structures to extremely subtle and patchy white matter alterations characterized by slight vacuolization of the white matter or slight to moderate increases in cellularity confined to the junction of cerebral cortex and white matter. Even fetuses that showed full recovery of all physiologic parameters, including electrocorticographic activity, demonstrated subtle but distinct white matter lesions. The gray matter, including the hippocampal neurons, was generally spared in these cases. Electrocorticographic parameters, duration of hypotension during asphyxia, and delayed recovery of blood lactate concentrations correlated well with the histologic grading of brain damage.

CONCLUSIONS

Asphyxia by partial umbilical cord occlusion in near-term fetal lambs produces variable neuropathologic changes. The mildest change is a white matter lesion characterized by vacuolization and loss of myelin or by increased cellularity in the damaged regions.

General movements in full-term infants with perinatal asphyxia are related to Basal Ganglia and thalamic lesions

OBJECTIVE

To correlate the site and severity of brain lesions seen on magnetic resonance imaging (MRI) with the quality of general movements in term infants with hypoxic-ischemic encephalopathy (HIE) and compare the prognostic value of general movements and MRI for motor outcome.

STUDY DESIGN

Early brain MRI scans in 34 term infants with HIE not treated with hypothermia were reviewed and scored for site of injury and lesion pattern by an experienced neuroradiologist. General movement quality and trajectories at 1 and 3 postnatal months were evaluated. Motor outcome was assessed at 24 months.

RESULTS

MRI scores for the basal ganglia and thalami, posterior limb of the internal capsule, white matter, and cortex and lesion patterns were correlated with 1-month and 3-month general movements and general movement trajectories; central gray matter scores were correlated most strongly with cramped-synchronized general movements and abnormal motor outcome. MRI scores were 100% sensitive and 72.2% specific for motor outcome, and cramped-synchronized general movements were 100% specific and 68.7% sensitive for motor outcome.

CONCLUSIONS

In term infants with HIE, the site and severity of brain lesions seen on early MRI are highly correlated with general movements. Central gray matter damage leads to cramped-synchronized general movements and poor motor outcome. Early MRI scans and general movements are complementary tools for predicting motor outcome.

Obstructive fibrinous tracheal pseudomembrane. A potentially fatal complication of tracheal intubation

A series of 10 consecutive cases presenting an obstructive fibrinous tracheal pseudomembrane (OFTP) as a complication of endo-tracheal intubation is presented. The patients developed a thick tubular, rubber-like, whitish pseudomembrane moulding the tracheal wall as a result of short-duration endotracheal intubation. This pseudomembrane firmly adhered to the tracheal wall at the site of the endotracheal cuff. Shortly after extubation, partial detachment of the proximal part of the pseudomembrane produced intermittent positional acute respiratory failure due to valve-manner tracheal obstruction. Immediate mechanical ablation was curative in nine patients, without secondary development of tracheal stenosis. One patient died from acute asphyxiation. The history and the pathological findings of these cases support the hypothesis that this lesion represents an early stage of ischemic tracheal wall injury related to the cuff pressure. Pulmonary physicians should be alerted on this poorly known complication of endotracheal intubation.

Hypothermia for 24 hours after asphyxic cardiac arrest in piglets provides striatal neuroprotection that is sustained 10 days after rewarming

The neuroprotective effect of hypothermia instituted after resuscitation from asphyxic cardiac arrest has not been studied in immature brain, particularly in a large animal model with recovery periods greater than 4 d. Moreover, protection from severe hypoxia seen with 3 h of hypothermia was reported to be lost when hypothermic duration was extended to 24 h in unsedated piglets, in contrast to the neuroprotection reported by 72 h of intrauterine head cooling in fetal sheep. Piglets (5-7 postnatal days) were subjected to asphyxic cardiac arrest followed by 24 h of either hypothermia (34 degrees C) or normothermia (38.5-39 degrees C). Comparisons were made with normothermic and hypothermic surgical sham animals without asphyxia. All of these groups were sedated, paralyzed, and mechanically ventilated for the first 24 h to prevent shivering and possible depletion of glucose stores. Hypothermia per se did not cause remarkable structural abnormalities. Ischemic damage was evaluated in putamen at 1 d of recovery without rewarming and at 11 d (10 d +/- SD after rewarming). Ischemic cytopathology affected 60 +/- 12% of neurons in putamen of normothermic animals compared with 9 +/- 6% in hypothermic animals at 1 d of recovery without rewarming. At 11 d of recovery from hypoxia-ischemia, the density of viable neurons (neuron profiles/mm2) in putamen was markedly reduced in normothermic animals (81 +/- 40) compared with hypothermic animals (287 +/- 22), which was the same as in sham normothermic (271 +/- 21), sham hypothermic (288 +/- 46) and naïve animals (307 +/- 51). These data demonstrate that 24 h of hypothermia at 34 degrees C with sedation and muscle relaxation after asphyxic cardiac arrest prevents necrotic striatal neuronal cell death in immature brain before rewarming, and that the effect is sustained at 11 d after injury without deleterious side effects.

Magnetic resonance imaging assessment of regional cerebral blood flow after asphyxial cardiac arrest in immature rats

Cerebral blood flow (CBF) alterations after asphyxial cardiac arrest (CA) are not defined in developmental animal models or humans. We characterized regional and temporal changes in CBF from 5 to 150 mins after asphyxial CA of increasing duration (8.5, 9, 12 min) in postnatal day (PND) 17 rats using the noninvasive method of arterial spin-labeled magnetic resonance imaging (ASL-MRI). We also assessed blood-brain barrier (BBB) permeability, and evaluated the relationship between CBF and mean arterial pressure after resuscitation. After all durations of asphyxia CBF alterations were region dependent. After 8.5- and 9-min asphyxia, intense subcortical hyperemia at 5 min was followed by return of CBF to baseline values by 10 mins. After 12-min asphyxia, hyperemia was absent and hypoperfusion reached a nadir of 38% to 65% of baselines with the lowest values in the cortex. BBB was impermeable to gadoteridol 150 mins after CA. CBF in the 12-min CA group was blood pressure passive at 60 min assessed via infusion of epinephrine. ASL-MRI assessment of CBF after asphyxial CA in PND 17 rats reveals marked duration and region-specific reperfusion patterns and identifies possible new therapeutic targets.

Postmortem lung weight in drownings: a comparison with acute asphyxiation and cardiac death

There are several controversial findings and arguments about the lung weight as a marker of drowning. The aim of the present study was to examine the difference in the lung weight and the amount of pleural effusion between freshwater and saltwater drownings (n=70 and n=75, respectively), in comparison with asphyxiation (n=85) and acute cardiac death (n=82), for the diagnosis of drowning. In drowning cases, a gradual postmortem time-dependent decrease in the lung weight and a reciprocal increase in the pleural effusion suggested postmortem transudation from the lungs. The decrease in the total value of the combined lung weight and the amount of pleural effusion was marked in saltwater immersion after 3 days postmortem, suggesting a leakage of the effusion out of the thoracic cavity under an osmotic effect of the immersion medium. In cases within 3 days postmortem, when the combined lung weight and amount of pleural effusion were added to estimate possible combined lung weight at the time of death, there was a gross difference among the causes of death: the value was the largest in saltwater drowning, followed by freshwater drowning, acute cardiac death and asphyxiation. However, the value depended on the gender and age of the subjects, suggesting a relation to the individual physical constitution and survival time or vital activity. These factors should be taken into consideration in evaluation of the lung weight in the diagnosis of drownings.

Homicidal asphyxia

Homicides due to asphyxia are relatively uncommon. To better understand the presentation of such cases, the files of the Bexar County Medical Examiner's Office were reviewed from January 1, 1985, through December 31, 1998, for all such homicides. A total of 133 cases were found. The largest category was ligature strangulation with 48 deaths (21 male, 27 female). Petechiae were present in the conjunctivae and/or sclerae in 86% of the cases; fractures of the hyoid and/or thyroid cartilage were present in 12.5%. There were a total of 41 deaths from manual strangulation (27 female, 14 male). Petechiae were present in 89% of the cases. In cases of manual strangulation, fractures of the hyoid, thyroid, or cricoid cartilage were found in all the male victims and slightly more than one half of the female victims. Twenty-six cases of suffocation were found; 20 of the victims were < or =2 years of age. Only 1 of these children had petechiae and/or scleral hemorrhage. Five deaths were due to choking. Three of the deaths involved adults who were gagged; 2 deaths involved infants with foreign material pushed into the mouth. Other categories of asphyxia were as follows: 9 deaths due to more than one form of asphyxia; 1 death due to hanging, and 3 deaths due to drowning. Rape was the motive in 66% of the female victims of ligature strangulation and 52% of those due to manual strangulation.

Patterns of non-firearm homicide

Sixty-two recent non-firearm homicides dealt with by an inner London public mortuary were studied. The majority of homicides involved stabbing--usually multiple wounds to the trunk. These were followed by blunt instrument homicides--nearly all involved multiple blows to the head, and asphyxiation--usually consisting of strangulation with a ligature being employed in the majority of cases. Homicides tended to occur during the evening and night in spring and early summer. Most victims were found to be in the 20-39 age group, with male victims outnumbering females in a 2:1 ratio. A marked difference in homicide pattern existed between the male and female victims. Males tended to fall victim to strangers encountered while socialising in and around bars and clubs. Females were most often killed by close acquaintances in domestic disputes at home.

Patho-anatomic findings in neck structures in asphyxiation due to hanging: a survey of 80 cases

By examining 80 consecutive cases of death due to hanging, fractures of the thyroid cartilage or the hyoid bone or both, were noted in 45%. Fracture of the cricoid cartilage did not occur. No fracture occurred below the age of 25, and the frequency was slightly increasing with increasing age. There was a preponderance of fractures in males. The highest incidence of fractures was noted in typical hangings, while incomplete hanging to a very great extent was combined with congestion to the face, especially if the location of the ligature was atypical. Typical hanging in general did not produce congestion. The lividity in the declivous areas became fixed at the earliest after 5-6 h suspension time, while after 12 h almost all the cases demonstrated fixed lividity in the distal parts, especially in the legs. There is slight indication that the frequency of fractures increases with the length of suspension time.

Cardiac troponin I (cTn I) and the postmortem diagnosis of myocardial infarction

In clinical practice several biochemical markers are used for the diagnosis of myocardial infarction. Because of its extremely high specificity for myocardial damage, cardiac troponin I (cTn I) is frequently used. The aim of this study was to evaluate the diagnostic efficacy of postmortem cTn I determinations in pericardial fluid and serum and to compare these results with other biochemical markers and with structural findings used to diagnose acute myocardial ischaemia. We studied 89 cadavers with a mean age of 51.38 +/- 2.04 (SD 19.27 years). Cases were allocated to 1 of 4 diagnostic groups depending on the probable intensity of myocardial damage and cause of death. In pericardial fluid we obtained statistically significant differences for the four biochemical parameters, while in serum myosin heavy chains and myoglobin showed statistically significant differences. The highest levels of biochemical markers in pericardial fluid were observed in subjects who had died from definite myocardial infarction.

The forensic significance of conjunctival petechiae

Conjunctival petechiae were mentioned in 227 (4.5%) of 5,000 consecutive autopsy reports of the Dade County Medical Examiner Department. They were most frequently observed in those who had died natural deaths (particularly due to cardiovascular disease), followed by those who had died from asphyxia, head injury, and central nervous system disorders. The incidence of conjunctival petechiae in victims of homicidal asphyxiation was 78%. These data suggest that conjunctival petechiae most often are the result of hypoxia coupled with an acute increase in cephalic vascular pressure. The latter factor may be the consequence of mechanical vascular obstruction or acute right heart failure.

Frequency of neck organ fractures in hanging

This study is a retrospective analysis of 307 accidental and suicidal hangings for the presence or absence of neck organ fractures. Approximately 9% of cases showed such fractures. This is in agreement with one prior study and in disagreement with others. The factor most likely to be predictive of fractures is advanced age. Gender, height of suspension, and ligature type do not seem to be of predictive value.

The pathological features and circumstances of death of lethal crush/traumatic asphyxia in adults--a 25-year study

A 25-year retrospective study of cases of crush/traumatic asphyxia autopsied at Forensic Science SA, Adelaide, Australia from 1980 to 2004 was undertaken. A total of 79 cases of crush asphyxia was found consisting of 63 males (80%) and 16 females (20%). The age range of the males was 19-86 years (mean=41.8 years) and of the females was 19-75 years (mean=38.6 years). In 18 cases the exact circumstances of death were unclear, leaving 61 cases in which details of the fatal episode were available. Major categories included vehicle crashes (N=37), industrial accidents (N=9), farm accidents (N=6) and entrapment beneath vehicles (N=5). Forty of the 79 victims (51%) had only very minor bruises and abrasions; 28 (35%) had evidence of chest compression with rib and sternal fractures and large areas of soft tissue bruising of the chest; 7 cases (9%) had other significant injuries or findings that had contributed to death. All of these victims had signs of crush asphyxia in the form of intense purple congestion and swelling of the face and neck, and/or petechial hemorrhages of the skin of the face and/or conjunctivae. The pattern of pathological findings of crush asphyxia was not influenced by the presence or absence of concomitant serious or lethal injuries. In 4 cases (5%) where the circumstances of the lethal episode were those of crush asphyxia there were no characteristic pathological findings. This study has shown that a high percentage of crush asphyxias may be caused by vehicle accidents. It has also demonstrated that on occasion fatal crush asphyxia may have to be a diagnosis of exclusion, made only when there are characteristic death scene findings, and no evidence of lethal natural diseases or injuries at autopsy, with negative toxicological screening.