Forensic aspects of post-mortem histological detection of amniotic fluid embolism.

Amniotic fluid embolism (AFE) continues to be one of the most feared and devastating complications of pregnancy. A reliable diagnosis can be made only upon histological examination. A detection of AFE every now and then has a relevant implication on medico-legal aspects of intrapartum or post-partum maternal death. However, there are only isolated reports in the literature concerning the detection interval of amniotic fluid elements after their transfer into the lungs. The objective of this study was to determine how long after the onset of clinical symptoms the elements of amniotic fluid may be detectable in the pulmonary circulation. An autopsy, as well as a histological and toxicological examination of 29 women, who died intrapartum or post-partum were performed. AFE was diagnosed in seven women (25%). The maximum survival time of the women with AFE and also the detection interval of AF in the pulmonary vasculature was 36 h. In the lungs of the women who did not die of AFE, amniotic fluid components were not found. Thus, there is no evidence for a physiologic occurrence of AFE. In women who die some days or even weeks after delivery as a consequence of a haemorrhagic shock following post-partum genital bleeding ensuing from uterine atony, AFE should be considered as a cause of a coagulopathy.

Death due to neurogenic shock following gastric rupture in an anorexia nervosa patient.

We report a case of fatal gastric rupture discovered after death, which developed due to a bulimic attack of a 19-year-old woman suffering from anorexia nervosa. An autopsy revealed an acute gastric dilatation and rupture without commonly observed ischemic damage of gastric wall structures. However, it may be difficult to determine the cause of death despite the marked findings. The death as a consequence of neurogenic shock accounts for all the results of gross examination and histologic analysis. This case is the first reported case of fatal gastric rupture of an anorectic patient discovered after death.

[Sudden death caused by an arterial hydatid embolism]. / Plötzlicher Tod durch arterielle Hydatidenembolie.

HISTORY: A 45-year-old woman from Turkey who had been living in Germany for 6 years, suddenly became short of breath, developed seizures and died within 2 minutes. There was no evidence of previous illness. INVESTIGATIONS: At autopsy a large hydatid and many other hydatids of varying sizes were found inside the left heart. Rupture of one of the hydatid cysts in the left atrium had caused embolism to the arterial system. The cyst walls showed typical laminar cuticular structure. The sediments of the cyst fluid contained scolices of Echinococcus granulosus, but no antibodies were demonstrated by indirect haemagglutination. DIAGNOSIS AND CONCLUSION: This is a rare case of Echinococcus granulosus infection, limited to the heart, which had followed an asymptomatic course until sudden death caused by arterial embolism of the hydatids. Such diagnosis should be considered in case of sudden death of persons from areas in which the disease is endemic.

Microscopic and thermal characterization of hydrogen peroxide killing and lysis of spores and protection by transition metal ions, chelators, and antioxidants.

Killing of bacterial spores by H(2)O(2) at elevated but sublethal temperatures and neutral pH occurred without lysis. However, with prolonged exposure or higher concentrations of the agent, secondary lytic processes caused major damage successively to the coat, cortex, and protoplast, as evidenced by electron and phase contrast microscopy. These processes were also reflected in changes in differential scanning calorimetric profiles for H(2)O(2)-treated spores. Endothermic transitions in the profiles occurred at lower temperatures than usual as a result of H(2)O(2) damage. Thus, H(2)O(2) sensitized the cells to heat damage. Longer exposure to H(2)O(2) resulted in total disappearance of the transitions, indicative of major disruptions of cell structure. Spores but not vegetative cells were protected against the lethal action of H(2)O(2) by the transition metal cations Cu, Cu, Co, Co, Fe, Fe, Mn, Ti, and Ti. The metal chelator EDTA was also somewhat protective, while o-phenanthroline, citrate, deferoxamine, and ethanehydroxydiphosphonate were only marginally so. Superoxide dismutase and a variety of other free-radical scavengers were not protective. In contrast, reducing agents such as sulfhydryl compounds and ascorbate at concentrations of 20 to 50 mM were highly protective. Decoating or demineralization of the spores had only minor effects. The marked dependence of H(2)O(2) sporicidal activity on moderately elevated temperature and the known low reactivity of H(2)O(2) itself suggest that radicals are involved in its killing action. However, the protective effects of a variety of oxidized or reduced transition metal ions indicate that H(2)O(2) killing of spores is markedly different from that of vegetative cells.

[The juxta-oral organ (Chievitz organ)--a sensory organ in the bucco-temporal area?]. / Das juxtaorale Organ (Chievitz-Organ)--ein sensibles Organ in der Buccotemporalregion?

Samples of a juxtaoral organ were examined immunohistochemically with antibodies against light-chain cytokeratin (KL-1), cytokeratin 19, desmin, chromogranin, neuron-specific enolase, and S-100 protein. The epithelial cells were found to be immunoreactive only with the two cytokeratin antibodies. Transmission electron microscopy was also performed. The results are best compatible with a mechanoreceptor function of the organ.

Purification and characterization of Klebsiella aerogenes UreE protein: a nickel-binding protein that functions in urease metallocenter assembly.

The Klebsiella aerogenes ureE gene product was previously shown to facilitate assembly of the urease metallocenter (Lee, M.H., et al., 1992, J. Bacteriol. 174, 4324-4330). UreE protein has now been purified and characterized. Although it behaves as a soluble protein, UreE is predicted to possess an amphipathic beta-strand and exhibits unusually tight binding to phenyl-Sepharose resin. Immunogold electron microscopic studies confirm that UreE is a cytoplasmic protein. Each dimeric UreE molecule (M(r) = 35,000) binds 6.05 + 0.25 nickel ions (Kd of 9.6 +/- 1.3 microM) with high specificity according to equilibrium dialysis measurements. The nickel site in UreE was probed by X-ray absorption and variable-temperature magnetic circular dichroism spectroscopies. The data are most consistent with the presence of Ni(II) in pseudo-octahedral geometry with 3-5 histidyl imidazole ligands. The remaining ligands are nitrogen or oxygen donors. UreE apoprotein has been crystallized and analyzed by X-ray diffraction methods. Addition of nickel ion to apoprotein crystals leads to the development of fractures, consistent with a conformational change upon binding nickel ion. We hypothesize that UreE binds intracellular nickel ion and functions as a nickel donor during metallocenter assembly into the urease apoprotein.

Homicide with a captive bolt pistol.

A homicide with a captive bolt pistol (slaughterer's gun) is reported. The construction and the function of this "humane killer" as well as the typical patterns of injury are described.

Heat killing of bacterial spores analyzed by differential scanning calorimetry.

Thermograms of the exosporium-lacking dormant spores of Bacillus megaterium ATCC 33729, obtained by differential scanning calorimetry, showed three major irreversible endothermic transitions with peaks at 56, 100, and 114 degrees C and a major irreversible exothermic transition with a peak at 119 degrees C. The 114 degrees C transition was identified with coat proteins, and the 56 degrees C transition was identified with heat inactivation. Thermograms of the germinated spores and vegetative cells were much alike, including an endothermic transition attributable to DNA. The ascending part of the main endothermic 100 degrees C transition in the dormant-spore thermograms corresponded to a first-order reaction and was correlated with spore death; i.e., greater than 99.9% of the spores were killed when the transition peak was reached. The maximum death rate of the dormant spores during calorimetry, calculated from separately measured D and z values, occurred at temperatures above the 73 degrees C onset of thermal denaturation and was equivalent to the maximum inactivation rate calculated for the critical target. Most of the spore killing occurred before the release of most of the dipicolinic acid and other intraprotoplast materials. The exothermic 119 degrees C transition was a consequence of the endothermic 100 degrees C transition and probably represented the aggregation of intraprotoplast spore components. Taken together with prior evidence, the results suggest that a crucial protein is the rate-limiting primary target in the heat killing of dormant bacterial spores.

Rhizobium lipopolysaccharide modulates infection thread development in white clover root hairs.

The interaction between Rhizobium lipopolysaccharide (LPS) and white clover roots was examined. The Limulus lysate assay indicated that Rhizobium leguminosarum bv. trifolii (hereafter called R. trifolii) released LPS into the external root environment of slide cultures. Immunofluorescence and immunoelectron microscopy showed that purified LPS from R. trifolii 0403 bound rapidly to root hair tips and infiltrated across the root hair wall. Infection thread formation in root hairs was promoted by preinoculation treatment of roots with R. trifolii LPS at a low dose (up to 5 micrograms per plant) but inhibited at a higher dose. This biological activity of LPS was restricted to the region of the root present at the time of exposure to LPS, higher with LPS from cells in the early stationary phase than in the mid-exponential phase, incubation time dependent, incapable of reversing inhibition of infection by NO3- or NH4+, and conserved among serologically distinct LPSs from several wild-type R. trifolii strains (0403, 2S-2, and ANU843). In contrast, infections were not increased by preinoculation treatment of roots with LPSs from R. leguminosarum bv. viciae strain 300, R. meliloti 102F28, or members of the family Enterobacteriaceae. Most infection threads developed successfully in root hairs pretreated with R. trifolii LPS, whereas many infections aborted near their origins and accumulated brown deposits if pretreated with LPS from R. meliloti 102F28. LPS from R. leguminosarum 300 also caused most infection threads to abort. Other specific responses of root hairs to infection-stimulating LPS from R. trifolii included acceleration of cytoplasmic streaming and production of novel proteins. Combined gas chromatography-mass spectroscopy and proton nuclear magnetic resonance analyses indicated that biologically active LPS from R. trifolii 0403 in the early stationary phase had less fucose but more 2-O-methylfucose, quinovosamine, 3,6-dideoxy-3-(methylamino)galactose, and noncarbohydrate substituents (O-methyl, N-methyl, and acetyl groups) on glycosyl components than did inactive LPS in the mid-exponential phase. We conclude that LPS-root hair interactions trigger metabolic events that have a significant impact on successful development of infection threads in this Rhizobium-legume symbiosis.

Involvement of a Collar Structure in Polar Growth and Cell Division of Strain DCB-1.

Microscopic methods were used to investigate the unique collar structure of the gram-negative sulfate-reducing bacterium, strain DCB-1. Polar cell growth apparently occurred from the collar. When the daughter cell was approximately equal in length to the mother cell and the collar was thus centrally located, cell division occurred within the collar region. Division was by a novel mechanism which conserved the collar of the mother cell and gave rise to a new collar of the daughter cell. Cells of DCB-1 were also found to contain stacked internal membranes and glycogen bodies.

Localization of the cytochrome cd1 and copper nitrite reductases in denitrifying bacteria.

The locations of cytochrome cd1 nitrite reductases in Pseudomonas aeruginosa and Pseudomonas fluorescens and copper nitrite reductases in Achromobacter cycloclastes and Achromobacter xylosoxidans were identified. Immunogold labeling with colloidal-gold probes showed that the nitrite reductases were synthesized exclusively in anaerobically grown (denitrifying) cells. Little immunogold label occurred in the cytoplasm of these four strains; most was found in the periplasmic space or was associated with cell membranes. Immunogold labeling of thin sections was superior to fractionation by osmotic shock for locating nitrite reductases. The results support models of dentrification energetics that require a periplasmic, not a cytoplasmic, location for nitrite reductases.

[Myoglobin concentrations of cadaver blood in fatal electric injuries]. / Myoglobinkonzentrationen des Leichenblutes bei Stromtodesfällen.

In cases of death due to electrical current frequently autopsies do not reveal makroscopic findings. Recent reports indicated, that an increased concentration of myoglobin in blood sampled from the heart and femoral vein as a sign of membraneous alteration related to electrical current passing the human body is applicable to prove death from electricity, as far as other factors extremely influencing myoglobin concentration can be excluded. Determination of myoglobin by radioimmunoassay performed on 5 cases of death caused by electrical current, 3 cases of sudden death due to heart disease and several other causes of death did not verify any correlation between myoglobin concentration and causes of death.

Influence of pH extremes on sporulation and ultrastructure of Sarcina ventriculi.

Distinct morphological changes in the ultrastructure of Sarcina ventriculi were observed when cells were grown in medium of constant composition at pH extremes of 3.0 and 8.0. Transmission electron microscopy revealed that at low pH (less than or equal to 3.0) the cells formed regular packets and cell division was uniform. When the pH was increased (to greater than or equal to 7.0), the cells became larger and cell division resulted in irregular cells that varied in shape and size. Sporulation occurred at high pH (i.e., greater than or equal to 8.0). The sporulation cycle followed the conventional sequence of development for refractile endospores, with the appearance of a cortex and multiple wall layers. The spores were resistant to oxygen, lysozyme, or heating at 90 degrees C for 15 min. Spores germinated within the pH range of 4.6 to 7.0.

Regulation of gene expression and cellular localization of cloned Klebsiella aerogenes (K. pneumoniae) urease.

The genes for Klebsiella aerogenes (K. pneumoniae) urease were cloned and the protein was overexpressed (up to 18% of total protein consisted of this enzyme) in several hosts. The small size of the DNA encoding urease (3.5 kb), the restriction map, and the regulation of enzyme expression directed by the recombinant plasmid are distinct from other cloned ureases. Nickel concentration did not affect urease gene expression, as demonstrated by the high levels of apoenzyme measured in cells grown in nickel-free media. However, nickel was required for urease activity. The overproducing recombinant strain was used for immunogold electron microscopic localization studies to demonstrate that urease is a cytoplasmic enzyme.