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Results for “Postmortem Changes”

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At least 271 records · Page 15Linked to original sources

PubMed2003

Dielectric properties of porcine brain tissue in the transition from life to death at frequencies from 800 to 1900 MHz.

Ten experiments on pigs were performed to investigate possible postmortem changes of the dielectric properties of brain gray matter in the frequency range of 800-1900 MHz. After keeping the animals in stable anaesthesia for at least 45 min, they were euthanatised by an intravenous injection of hypertonic potassium chloride (KCl), causing cardiac arrest within 3 min. Measurements of the dielectric properties were performed repeatedly from at least 45 min prior to death to 18 h after euthanasia. The anaesthesia regimen was chosen to minimize influence on brain tissue characteristics such as brain water content, intracranial blood volume, and cerebral blood flow. The data showed a decline of mean gray matter equivalent conductivity of about 15% at 900 MHz and about 11% at 1800 MHz within the first hour after death. The decline in permittivity was less pronounced (about 3-4%) and almost frequency independent. The results indicate that in vitro measurements of dielectric properties of brain tissue underestimate equivalent conductivity as well as permittivity of living tissue. These changes may affect the generally accepted data of dielectric properties of brain tissue widely used in RF dosimetry.

Animals↗

PubMed1988

Loss of cholinergic muscarinic receptors in the frontal cortex of alcohol abusers.

Alcohol abuse causes impairment of cognitive function ranging from mild forms to end-stage dementia. Alcohol-related dementia accounts for nearly 20% of all admissions to state mental hospitals and may result from head trauma, thiamine deficiency, Alzheimer's, and other brain diseases that can be diagnosed conclusively only at autopsy. However, we postulate that after all these conditions have been excluded, an "alcohol encephalopathy" remains. This is characterized by impaired synaptic function, which underlies the continuum of impaired intellectual function. We found in 79 histologically normal brains of a nondemented general hospital population a 40% decrease in the density of cholinergic muscarinic receptors in the frontal cortex of alcoholics when compared with matched controls of the same age. Only alcohol abuse and not aging, postmortem changes, medications, clinical (including liver) diseases, or differences in causes of death could account for this loss.

Age Factors↗

PubMed2003

Hepatic portal venous gas and hyper-dense aortic wall as postmortem computed tomography finding.

Postmortem computed tomography (PMCT) is useful for diagnosis of cause of death not only by emergency physicians but also medical examiners or police surgeons conducting postmortem studies. However, postmortem biological conditions are quite different from those in the living body. Hepatic portal venous gas (HPVG) and a hyperdense aortic wall (HDAW) are often found by PMCT, although no significant autopsy findings are evident in the liver or aorta. In this study we compared the findings of PMCT with those obtained at autopsy, and discussed the cause of these PMCT features. PMCT was conducted in 12 autopsy cases, comprising eight cases of natural death and four of unnatural death. HPVG was seen in five cases and HDAW in seven. In the cases showing HPVG, visceral abdominal injury, bowel distention or acute circulatory dysfunction was found at autopsy. In the cases showing HDAW, atherosclerosis or an increase in blood viscosity due to dehydration or postmortem changes was evident. Although the precise causes of these PMCT findings are not completely clear, the changes evident at autopsy provide some clues.

Adolescent↗

PubMed1992

Discrepancy between estimated and actual time elapsed after death of a severed head.

A severed head which had been wrapped in seven plastic bags and set in concrete in an airtight insulated plastic box was found approximately 22 months after the occurrence of death. Ammonium magnesium phosphate had formed and on the basis of this and other observed postmortem changes, time elapsed after death was estimated to be from 2 weeks to 6 months. The absence of oxygen is thought to have contributed significantly to the great discrepancy between estimated and actual time elapsed after death.

Adult↗

PubMed1993

Application of nuclear magnetic resonance (NMR) spectroscopy to legal medicine--ATP quantitation in tissue with 31P-NMR.

NMR spectroscopy can be used to identify and determine various molecular species in organs and tissues, and can provide information on the condition of their presence. We used NMR spectroscopy to examine postmortem changes in rabbits. ATP levels could be determined with ATP beta-position phosphorus atom signals in 31P-NMR spectra of tissue samples used as parameters. Changes over time in myocardial and limb muscular ATP levels were examined from just after death due to various causes to 7 hours after death, and the following results were obtained: 1. Myocardial ATP levels were low in groups with pronounced anoxia just before death. 2. Among groups with identical causes of death, decreases in myocardial ATP levels were larger the more pronounced was anoxia. Findings 1 and 2 are applicable to determination of acute cause of death considered otherwise difficult to detect in legal medical practice. 3. The decrease in ATP level just after death was smaller in limb muscles than in myocardium, and changes over time in the decrease in ATP after death could be observed. This finding may be applicable to the estimation of passage of time after death, a problem of great import in legal medicine.

Adenosine Triphosphate↗

PubMed1983

Chromatographic analysis of glutamic acid decarboxylase in biological samples.

A number of non-chromatographic and chromatographic methods for analysis of GAD activity in biological tissues have been described. The majority of these chromatographic methods utilize the analysis of GABA formed from incubation homogenates. Depending upon the analytical technique selected, limits of detection range from nanogram to picogram levels of GABA. Also discussed have been some of the commonly associated problems and their resolution with sample collection, postmortem changes and alternative pathways of CO2 and GABA production which can lead to errors in accurate determination of GAD activity in biological samples.

4-Aminobutyrate Transaminase↗

PubMed1998

Increased tau protein level in postmortem cerebrospinal fluid.

Microtubule-associated protein tau has been reported to be significantly increased in cerebrospinal fluid (CSF) of the patients with Alzheimer's disease (AD), which suggests that it is possibly a biological marker for the diagnosis of AD. The underlying mechanism of the increased tau level in CSF, however, is not known. In this study, the tau levels were compared between antemortem and postmortem CSF. The postmortem tau levels in CSF were significantly increased in all groups including AD, neurological control, and nondemented control. A striking elevation of CSF tau was observed during the postmortem change with the nondemented subjects. These findings may offer some insight into the understanding of the mechanism of the increased tau level in CSF with AD and other related disorders.

Aged↗

PubMed1990

Sulfide concentrations in postmortem mammalian tissues.

Postmortem changes in sulfide concentrations in body tissues were examined in autopsied rats exposed to hydrogen sulfide concentrations of 550 to 650 ppm, and in nonexposed rats and humans. Analyses were made by gas chromatography, following an extractive alkylation. Sulfide concentrations in the blood, liver, and kidneys of rats increased in both the exposed and nonexposed groups, depending on the lapse of time after death. On the other hand, the lung, brain, and muscle showed little or no change in sulfide concentration with elapse of time after death. The data obtained from human tissues were almost the same as those for rats, except data for blood, in which no or little increase of sulfide was observed.

Animals↗

PubMed1993

[Reconstruction of the nutritional behavior based on trace elements in human skeletal remains. A critical overview].

Trace element analysis of human skeletal remains is an important tool in paleonutritional studies, providing unique information on 1) diachronic shifts and synchronous dietary differentiations within populations, as well as 2) paleodemographic variables, particularly the age of weaning. However, the initial expectations have not been fully met, the last 15 years' continued research has rather been characterized by a growing awareness of basic intricacies of the method. Firstly, postmortem changes in bone chemistry may lead to misinterpretations. Moreover, the theoretical basis for these interpretations is not as solid as it should to warrant unequivocal results. The main features of these diagenetic and interpretative problems are discussed in the present paper, followed by an evaluation of the potential applications of the technique.

Austria↗

PubMed1977

Microwave fixation of brain tissue as a neurochemical technique- a review.

Microwave devices have been developed for rapidly inactivating brain enzymes by focusing the power output into the heads of small laboratory animals. The rapid inactivation achieved prevents postmortem changes and permits the measurement of neurochemicals such as acetylcholine at concentrations close to those obtained in vivo. The technique promises the assay of neurochemical parameters not possible before.

5-Hydroxytryptophan↗

PubMedDate not supplied

[Dismemberment with unusual preservation of cadaver parts].

Report on a case of criminal dismembering of a corpse and the effect of vinyl on postmortem changes. Two years after murder a dismembered body, the body parts wrapped into plastic bags, were found buried 30-50 cm deep into loose earth. The whole body as well as the inner organs were very well preserved. Obviously the air-proof conditions in the plastic bag were a supporting factor for the good preservation.

Adult↗

PubMed1990

Beta-receptors and adenylate cyclase: comparison of nonischemic, ischemic, and postmortem tissue.

We compared the effects of myocardial ischemia and postmortem changes on beta-adrenergic receptors and their coupling to adenylate cyclase activity. The effects of 1 h of left circumflex coronary artery occlusion were examined in eight conscious calves, which were then anesthetized with pentobarbital sodium, and the left ventricle was divided into nonischemic and ischemic regions. A crude membrane fraction was prepared from each region and from the nonischemic tissue 1 h postmortem. beta-Adrenergic receptor density increased (152 +/- 55%) and decreases in basal (-21 +/- 6.1%), isoproterenol-stimulated (-25 +/- 8.0%), 5'-guanylylimidodiphosphate [Gpp(NH)p]-stimulated (-17 +/- 5.8%), fluoride-stimulated (-26 +/- 5.8%), and forskolin-stimulated (-31 +/- 8.4%) adenylate cyclase activities were observed in the ischemic myocardium compared with nonischemic myocardium. Similarly, in postmortem samples, beta-adrenergic receptor density rose 58 +/- 16%, whereas decreases in basal (-48 +/- 8.7%), isoproterenol-stimulated (-61 +/- 7.8%), Gpp(NH)p-stimulated (-58 +/- 7.0%), fluoride-stimulated (-64 +/- 6.1%), and forskolin-stimulated (-52 +/- 6.2%) adenylate cyclase activities were observed. Agonist-binding competition curves with isoproterenol were shifted, indicating that beta-adrenergic receptors were binding agonists with low affinity in both the ischemic and postmortem myocardium. The marked, but directionally opposite, changes in receptor density and adenylate cyclase that occur postmortem indicate the importance of prompt processing of tissues. The striking similarity in response of beta-adrenergic receptor agonist and antagonist binding and adenylate cyclase activity in ischemic and postmortem tissue raises the speculation that similar mechanisms may operate under both conditions.

Adenylyl Cyclases↗

PubMed1978

Identification of endogenous gamma-hydroxybutyrate in human and bovine brain and its regional distribution in human, guinea pig and rhesus monkey brain.

Gamma-Hydroxybutyric acid (GHB), a compound that has interesting neuropharmacological actions when administered systemically, was shown by means of gas chromatography-mass spectrometry to be present in postmortem samples of human brain in concentrations ranging from 2 to 20 nmol/g. Tissue samples from the basal ganglia contained 2 to 3 times as much GHB as tissue samples from cortical regions. The regional brain distribution of GHB was examined in the guinea pig and rhesus monkey and found to parallel the distribution observed in human brain. The levels of GHB found in the regional areas of human and monkey brain investigated were higher than the levels found in similar regions of guinea-pig brain. Additional studies demonstrated that there is a slow postmortem increase (about 2-fold) in the endogenous levels of GHB in bovine caudate and guinea-pig brain which is maximal about 6 hr postmortem. This postmortem increase could in part explain the higher levels of GHB found in human brain. However, postmortem changes could not account for the large differences observed in the levels of GHB found in bovine caudate and those found in guinea-pig, monkey and human caudate. Only traces of GHB could be detected in human blood and cerebrospinal fluid.

Animals↗

PubMed1991

Hypoxanthine levels in vitreous humor: evidence of hypoxia in most infants who died of sudden infant death syndrome.

Postmortem changes of the hypoxanthine in vitreous humor in humans were investigated. Hypoxanthine is formed from hypoxic degradation of adenosine monophosphate. Repeated sampling was performed in 13 deceased adults. Keeping the bodies at +6 degrees C, the increase of the hypoxanthine levels was estimated to 3.5 mumol/L per hour when sampling was started more than 12 hours after death (range 2.8 to 5.6 mumol/L per hour). Results of hypoxanthine measurements from vitreous humor in 73 infants with sudden infant death syndrome, 17 infants and children who died sudden violent deaths, and 6 neonates who died suddenly without hypoxemia prior to death were corrected according to the expected postmortem hypoxanthine increase. The time between death and autopsy was similar in the three groups studied. The corrected median hypoxanthine level in the group with sudden infant death syndrome was 227 mumol/L, which is significantly higher than in the other groups; 22 mumol/L in the group who had violent deaths (P less than .01), and 0 mumol/L in the neonate group (P less than .01). The findings seem to confirm that sudden infant death is preceded by a relatively long period of tissue hypoxia in most cases.

Aged↗

PubMed1989

[Roentgen identification of unknown cadavers and living persons].

Four cases of successful x-ray identification of unknown dead with progressed postmortem changes are reported. Some of the x-ray plates are 25 years old and have been taken during growth process. Skull and spine are especially qualified for identification because the skeleton shows individual, highly specific markers in these regions which do not change during live and after death. The exclusion of identity was possible with regard to a 50 years old patient. She presented a 19 years old urogram as her own to receive a pension after an occupational accident in 1970. Two other cases of x-ray identification (tibia operation and skull) have been already described by us (1988).

Adult↗

PubMed1987

Acoustic transfer characteristics in human middle ears studied by a SQUID magnetometer method.

The middle-ear transfer characteristics for sound in 14 human temporal bones were determined using a SQUID magnetometer method. With this method, the cochlea and middle ear remain intact. Postmortem changes were studied using a guinea pig. The mass-loading effects of the applied magnets were determined and were found to be negligible. The mean umbo displacement was equal to the mean of six other studies. Lever ratios varied between the individual temporal bones and as a function of frequency.

Acoustic Stimulation↗

PubMed1991

Microscopical study on estimation of time since death in skeletal remains.

For the purpose of estimating time since death in skeletal remains, postmortem changes in human compact bones were examined by microradiography and electron microscopy. The UV-fluorescence of the peripheral zone of compact bone was also examined by microscopic spectrophotometry. Microradiographic examination revealed no morphological changes in bones left in the open air for long periods, except one of 15 years since death. In bones left in the soil, vacuoles of 5-10 microns diameter, which contained a honeycomb-like structure formed by small vacuoles of 0.5-1 microns diameter, were found in the peripheral zone of the substantia compacta approximately 5 years since death, and in bones of 6 years or more, this change extended to the mid-zone. In bones left in the sea for 4-5 years, vacuoles of 5-10 microns diameter were observed in the outer peripheral zone of the substantia compacta. The relative intensity of UV-fluorescence in bones dwindled with time since death and the correlation coefficient was considerably high.

Bone and Bones↗

PubMed1981

[Possibility of studying lipoperoxidation processes in surviving tissues].

A study was made of postmortem changes in the activity of "antioxidative" enzymes and in the content of primary and secondary products of lipid peroxidation in rabbit tissues (aorta, liver). It was found that the content of primary and secondary products of lipid peroxidation in the liver sharply rises already 1.5 h after the animals were sacrificed whereas no significant changes developed in the aorta over 9 hours. The activity of the "antioxidative" enzymes in the aorta or liver remains unchanged during these hours. Possibilities are discussed of studying the activity of superoxide dismutase and glutathion peroxidase, and the products of lipid peroxidation in cadaveric material obtained on rapid autopsy of suddenly deceased people.

Animals↗