Corpuls cpr resuscitation device generates superior emulated flows and pressures than LUCAS II in a mechanical thorax model.

The provision of sufficient chest compression is among the most important factors influencing patient survival during cardiopulmonary resuscitation (CPR). One approach to optimize the quality of chest compressions is to use mechanical-resuscitation devices. The aim of this study was to compare a new device for chest compression (corpuls cpr) with an established device (LUCAS II). We used a mechanical thorax model consisting of a chest with variable stiffness and an integrated heart chamber which generated blood flow dependent on the compression depth and waveform. The method of blood-flow generation could be changed between direct cardiac-compression mode and thoracic-pump mode. Different chest-stiffness settings and compression modes were tested to generate various blood-flow profiles. Additionally, an endurance test at high stiffness was performed to measure overall performance and compression consistency. Both resuscitation machines were able to compress the model thorax with a frequency of 100/min and a depth of 5 cm, independent of the chosen chest stiffness. Both devices passed the endurance test without difficulty. The corpuls cpr device was able to generate about 10-40% more blood flow than the LUCAS II device, depending on the model settings. In most scenarios, the corpuls cpr device also generated a higher blood pressure than the LUCAS II. The peak compression forces during CPR were about 30% higher using the corpuls cpr device than with the LUCAS II. In this study, the corpuls cpr device had improved blood flow and pressure outcomes than the LUCAS II device. Further examination in an animal model is required to prove the findings of this preliminary study.

Corpuls CPR Generates Higher Mean Arterial Pressure Than LUCAS II in a Pig Model of Cardiac Arrest.

According to the European Resuscitation Council guidelines, the use of mechanical chest compression devices is a reasonable alternative in situations where manual chest compression is impractical or compromises provider safety. The aim of this study is to compare the performance of a recently developed chest compression device (Corpuls CPR) with an established system (LUCAS II) in a pig model. Methods. Pigs (n = 5/group) in provoked ventricular fibrillation were left untreated for 5 minutes, after which 15 min of cardiopulmonary resuscitation was performed with chest compressions. After 15 min, defibrillation was performed every 2 min if necessary, and up to 3 doses of adrenaline were given. If there was no return of spontaneous circulation after 25 min, the experiment was terminated. Coronary perfusion pressure, carotid blood flow, end-expiratory CO2, regional oxygen saturation by near infrared spectroscopy, blood gas, and local organ perfusion with fluorescent labelled microspheres were measured at baseline and during resuscitation. Results. Animals treated with Corpuls CPR had significantly higher mean arterial pressures during resuscitation, along with a detectable trend of greater carotid blood flow and organ perfusion. Conclusion. Chest compressions with the Corpuls CPR device generated significantly higher mean arterial pressures than compressions performed with the LUCAS II device.

Reliability of aortic MRI at 3 Tesla in patients with acute cryptogenic stroke.

OBJECTIVES: To evaluate a new three dimensional (3D) MRI protocol for the reliable detection of aortic high risk plaques compared with transoesophageal echocardiography (TOE) and to test the reliability of additional MRI in stroke of undetermined aetiology. METHODS: 74 acute stroke patients were examined by both TOE and MRI at 3 Tesla with special regard to aortic high risk plaques (ie, > OR = 4 mm, superimposed thrombi). ECG synchronised pre- and post-contrast T1 weighted 3D imaging (spatial resolution approximately 1 mm3) covering the thoracic aorta was employed. In plaques > OR = 3 mm, additional two dimensional T2 imaging and time resolved (CINE) imaging sequences were performed. Aetiology of brain ischaemia was classified according to modified TOAST (Trial of Org 10172 in Acute Stroke Treatment) criteria. Aortic high risk embolic sources detected by MRI in patients with cryptogenic stroke were evaluated. RESULTS: Differences in maximum aortic wall thickness for TOE and MRI were not statistically significant for all aortic segments. The overall number of high risk plaques detected by MRI (n = 74) was substantially higher compared with TOE (n = 47). Most noticeably, MRI identified aortic high risk pathologies in 8/26 (30.8%) patients with cryptogenic stroke after standard diagnostics, including TOE (n = 2: dissection or thrombus; n = 6: plaques > OR = 4 mm). CONCLUSIONS: Our results demonstrate the feasibility of this 3D MRI protocol for the reliable detection of aortic high risk plaques in acute stroke patients. Because of improved visualisation of the aortic arch and the detection of additional embolic sources not seen by standard diagnostics, this novel technique may become a valuable tool for future patients with cryptogenic stroke.

Brain activation responses to subliminal or supraliminal rectal stimuli and to auditory stimuli in irritable bowel syndrome.

Visceral hypersensitivity in irritable bowel syndrome (IBS) has been associated with altered cerebral activations in response to visceral stimuli. It is unclear whether these processing alterations are specific for visceral sensation. In this study we aimed to determine by functional magnetic resonance imaging (fMRI) whether cerebral processing of supraliminal and subliminal rectal stimuli and of auditory stimuli is altered in IBS. In eight IBS patients and eight healthy controls, fMRI activations were recorded during auditory and rectal stimulation. Intensities of rectal balloon distension were adapted to the individual threshold of first perception (IPT): subliminal (IPT -10 mmHg), liminal (IPT), or supraliminal (IPT +10 mmHg). IBS patients relative to controls responded with lower activations of the prefrontal cortex (PFC) and anterior cingulate cortex (ACC) to both subliminal and supraliminal stimulation and with higher activation of the hippocampus (HC) to supraliminal stimulation. In IBS patients, not in controls, ACC and HC were also activated by auditory stimulation. In IBS patients, decreased ACC and PFC activation with subliminal and supraliminal rectal stimuli and increased HC activation with supraliminal stimuli suggest disturbances of the associative and emotional processing of visceral sensation. Hyperreactivity to auditory stimuli suggests that altered sensory processing in IBS may not be restricted to visceral sensation.

Direct determination of selenium and other trace elements in serum samples by ICP-MS.

Selenium belongs to a group of trace elements of special interest in biological samples for clinical diagnosis. Selenium has antioxidizing functions and is essential for providing the organism with triiodothyronine produced from thyroxine. Among several analytical techniques used to determine the Se concentration in serum, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) has been used in the past because of its high sensitivity. Interference problems originating from different ions on the major Se isotopes have been described to be a limiting factor for the direct determination of Se in these matrices. Standard addition calibration or isotope dilution is often required to overcome carbon-enhanced ionisation effects in biological sample matrices. In most cases, the typical serum sample volume which is available for the analysis is limited to 0.5 ml or less, making multiple sample preparation for standard addition calibration impractical. Isotope dilution requires enriched isotopes and substantial sample preparation. Furthermore, the approximate Se concentration in every sample has to be known to adjust the appropriate amount of spike to each sample. Matrix matching with methanol has been described to overcome ionisation effects but we found limiting factors of this application when other trace elements are also determined within one sample run. This paper describes an effective sample preparation method which allows the direct determination of Se in serum without limiting the analytical capabilities for the additional determination of Al, Cu, Ni, Co, Cd, Mn and Zn in a single sample run by ICP-MS. Optimization procedures are presented and results of the analysis of reference samples are discussed, with a comparison of more than 150 serum data with those obtained by the GF-AAS method.

A mono phenylalanine-based motif (F790) and a leucine-dependent motif (LI760) mediate internalization of furin.

The eukaryotic endoprotease furin, a member of the subtilisin-related family of prohormone convertases, is synthesized and transported within the constitutive secretory pathway to the plasma membrane, from where it recycles to the trans-Golgi network (TGN). Previous studies showed that TGN-residence and recycling are mediated by the cytoplasmic tail. Two targeting determinants have been described so far, the acidic signal CPSDSEEDEG783 containing two casein kinase II (CKII) phosphorylation sites and the internalization signal YKGL765. Refined analyses of the cytoplasmic domain of furin, which was mutagenized and tagged to the influenza hemagglutinin and to the membrane cofactor protein (CD46) as reporter molecules reveal two additional internalization determinants, a leucine-isoleucine signal, LI760, and a mono phenylalanine-based motif at F790, which functions without any specific neighboring amino acid sequence. Both signals are capable of independently mediating internalization, as has been shown previously for the tyrosine-based signal. Thus, furin internalization is mediated by at least three independent endocytosis signals.

Two independent targeting signals in the cytoplasmic domain determine trans-Golgi network localization and endosomal trafficking of the proprotein convertase furin.

Furin, a subtilisin-like eukaryotic endoprotease, is responsible for proteolytic cleavage of cellular and viral proteins transported via the constitutive secretory pathway. Cleavage occurs at the C-terminus of basic amino acid sequences, such as R-X-K/R-R and R-X-X-R. Furin was found predominantly in the trans-Golgi network (TGN), but also in clathrin-coated vesicles dispatched from the TGN, on the plasma membrane as an integral membrane protein and in the medium as an anchorless enzyme. When furin was vectorially expressed in normal rat kidney (NRK) cells it accumulated in the TGN similarly to the endogenous glycoprotein TGN38, often used as a TGN marker protein. The signals determining TGN targeting of furin were investigated by mutational analysis of the cytoplasmic tail of furin and by using the hemagglutinin (HA) of fowl plague virus, a protein with cell surface destination, as a reporter molecule, in which membrane anchor and cytoplasmic tail were replaced by the respective domains of furin. The membrane-spanning domain of furin grafted to HA does not localize the chimeric molecule to the TGN, whereas the cytoplasmic domain does. Results obtained on furin mutants with substitutions and deletions of amino acids in the cytoplasmic tail indicate that wild-type furin is concentrated in the TGN by a mechanism involving two independent targeting signals, which consist of the acidic peptide CPSDSEEDEG783 and the tetrapeptide YKGL765. The acidic signal in the cytoplasmic domain of a HA-furin chimera is necessary and sufficient to localize the reporter molecule to the TGN, whereas YKGL is a determinant for targeting to the endosomes. The data support the concept that the acidic signal, which is the dominant one, retains furin in the TGN, whereas the YKGL motif acts as a retrieval signal for furin that has escaped to the cell surface.

Evolutionary aspects of cytochrome c oxidase.

The presence of additional subunits in cytochrome oxidase distinguish the multicellular eukaryotic enzyme from that of a simple unicellular bacterial enzyme. The number of these additional subunits increases with increasing evolutionary stage of the organism. Subunits I-III of the eukaryotic enzyme are related to the three bacterial subunits, and they are encoded on mitochondrial DNA. The additional subunits are nuclear encoded. Experimental evidences are presented here to indicate that the lower enzymatic activity of the mammalian enzyme is due to the presence of nuclear-coded subunits. Dissociation of some of the nuclear-coded subunits (e.g. VIa) by laurylmaltoside and anions increased the activity of the rat liver enzyme to a value similar to that of the bacterial enzyme. Further, it is shown that the intraliposomal nucleotides influence the kinetics of ferrocytochrome c oxidation by the reconstituted enzyme from bovine heart but not from P. denitrificans. The regulatory function attributed to the nuclear-coded subunits of mammalian cytochrome c oxidase is also demonstrated by the tissue-specific response of the reconstituted enzyme from bovine heart but not from bovine liver to intraliposomal ADP. These enzymes from bovine heart and liver differ in the amino acid sequences of subunits VIa, VIIa, and VIII. The results presented here are taken to indicate a regulation of cytochrome c oxidase activity by nuclear-coded subunits which act like receptors for allosteric effectors and influence the catalytic activity of the core enzyme via conformational changes.

Different isozymes of cytochrome c oxidase are expressed in bovine smooth muscle and skeletal or heart muscle.

Cytochrome c oxidase (COX) was isolated from bovine smooth muscle (rumen), and compared with the enzyme from bovine liver, heart and skeletal muscle. A new isozyme of COX was found to be expressed in smooth muscle, which differs from the isozyme in liver and heart or skeletal muscle. SDS-PAGE as well as N-terminal amino acid sequencing of separated subunits from gel bands revealed the expression of the liver isoforms for subunits VIa and VIII and of the heart isoform for subunits VIIa in COX from smooth muscle.

Tissue- and species-specific expression of cytochrome c oxidase isozymes in vertebrates.

Cytochrome c oxidase was isolated from brown fat tissue of the rat and compared with the isozymes from rat liver and heart, which differ at least in subunits VIa and VIII. ELISA titrations of COX from the three tissues with monospecific antisera to all 13 subunits of the rat liver enzyme showed differences between the three enzymes. The N-terminal amino-acid sequence analysis of subunits VIa and VIII from SDS-PAGE gel bands of the three enzymes indicates the occurrence of three different isozymes in the rat. N-terminal amino-acid sequence analysis of subunits VIa and VIII from cytochrome c oxidase of bovine and human heart demonstrates also species-specific differences in the expression of the 'liver-type' and 'heart-type' of subunits VIa and VIII.

Evolution of cytochrome c oxidase.

The current view on the regulatory function of nuclear-encoded subunits of cytochrome c oxidase from higher evolved organisms is presented. The activity of monomeric laurylmaltoside-dissolved, but not of reconstituted cytochrome c oxidase, is strongly affected by anions accompanied by a conformational change of the enzyme, as shown by changed visible spectra. Addition of uncoupler to proteoliposomes induces the same anion sensitivity as obtained with the soluble enzyme, suggesting dissociation of the dimeric membrane-bound enzyme by uncoupler. Nucleotides are suggested to regulate cytochrome c oxidase activity at 3 different sites: 1) Interaction of ATP with a cytosolic site (outside) increases the Km for cytochrome c in the enzyme from bovine heart and Paracoccus denitrificans; 2) binding of ADP at a matrix site decreases, and 3) binding of ATP at another matrix site increases the Km for cytochrome c of the mammalian enzyme.

Analysis of the Cu, Fe, and Zn contents in cytochrome C oxidases from different species and tissues by proton-induced X-ray emission (PIXE).

The Cu, Fe and Zn contents in isolated cytochrome c oxidase preparations from heart, liver, diaphragm or kidney of bovine, pig and rat was measured by proton-induced X-ray emission (PIXE). The average Cu/2Fe ratio was 2.73 and Zn/2Fe ratio 0.98. Correspondingly a Cu/Zn ratio of 2.76 was found. Dialysis of the bovine heart enzyme against increasing EDTA concentrations up to 30 mM did not change this result. It is concluded that all isozymes of mammalian cytochrome c oxidase contain 3 Cu, 2 Fe and 1 Zn per monomeric catalytic unit.

Tissue-specific and species-specific distribution of -SH groups in cytochrome c oxidase subunits.

Cytochrome c oxidase was isolated from pig, bovine, rat and human tissues including liver, heart, diaphragm and kidney. The native and the sodium-dodecyl-sulfate (SDS)-dissociated enzymes were labelled under optimal conditions with N-ethyl-[2,3-14C]maleimide before and after reduction with dithiothreitol, separated into 13 subunits by SDS gel electrophoresis and the radioactive bands were visualized by fluorography. In some cases the radioactive bands were cut out and counted. All isozymes were labelled in subunits I, III, Va and VIIb, and in subunit II after reduction. Labelling of subunit Vb was equivocal, and in no case were subunits IV and VIc labelled. All other subunits were labelled tissue-specifically and/or species-specifically. No differences were found between labelling of the native and SDS-dissociated enzyme. By relating the molar amount of bound N-ethylmaleimide to the known amount of cysteines in subunits of bovine heart cytochrome c oxidase, the percentage of -SH group reactivity was calculated. Only the cysteine of subunit Va was found to be 100% reactive. The distinct and different reactivity of subunit VIIb as compared to subunits VIIa and VIIc clearly establishes this polypeptide as an independent subunit of mammalian cytochrome c oxidase.

Missile embolus of the portal vein.

A missile embolus, an extremely rare lesion, presents an unusual and challenging problem for the clinician. A case is discussed in which a patient sustained a gunshot wound of the portal vein, and the bullet entered the portal venous system and then lodged in the superior mesenteric vein. The portal vein injury was repaired. The missile then migrated into the right branch of the portal vein and was not extracted. The patient recovered. This appears to be the first reported case of a missile embolus of the portal venous system.

Different reactivity of carboxylic groups of cytochrome c oxidase polypeptides from pig liver and heart.

Cytochrome c oxidase isolated from pig liver and heart was incubated with 1-ethyl-3-[3-(dimethyl-amino)propyl]carbodiimide and [14C]glycine ethyl ester in the presence and absence of cytochrome c. Labelling of individual subunits was determined after separation of the enzyme complexes into 13 polypeptides by SDS-gel electrophoresis. Polypeptide II and additional but different polypeptides were labelled in the liver and in the heart enzyme. Labelling of polypeptide II and of some other polypeptides could be partially or completely suppressed by cytochrome c. From the data two conclusions can be drawn: In addition to polypeptide II, other polypeptides take part in the binding of cytochrome c to cytochrome c oxidase; the binding domain for cytochrome c is different in pig liver and heart cytochrome c oxidase.

Chromatofocussing and centrifugal reconstitution as tools for the separation and characterization of the Na+-cotransport systems of the brush-border membrane.

Chromatofocussing was used for the separation of brush-border membrane proteins from calf kidney into 4 or 5 fractions over the pH range 4.0 to 7.4. These fractions were reconstituted into proteoliposomes by gradient centrifugation. Determination of the sodium-dependent solute uptake by proteoliposomes reconstituted from different chromatofocussed fractions showed that the sodium-D-glucose cotransport system was present in the fraction eluted between pH 5.3 and 5.8, and that the sodium-phosphate cotransport was present in fractions eluted between pH 4.6 and 5.3 and between pH 5.8 and 6.6, sodium-alanine cotransport could be detected in almost all fractions. Marker enzymes of the brush-border membrane, such as alkaline phosphatase, gamma-glutamyltransferase and aminopeptidase M etc. were also found to be eluted at pH 7.0-7.4, 4.0-4.1 and 5.6-5.8, respectively. These results suggest that chromatofocussing is a promising tool for the separation of membrane proteins and for pre-purification of the sodium-D-glucose cotransport system. It can be further concluded that the sodium-dependent phosphate transport across the brush-border membrane is not dependent upon alkaline phosphatase activity.

[Acute stress ulcer in an abusing family]. / Ulcère aigu de stress dans une famille maltraitante.

The authors report one case of a 3 1/2 year-old battered boy, with acute giant stress ulcer on the lesser curvature of the stomach. Hematemesis was the presenting symptom. Diagnosis was established after fiberoptic endoscopy and upper G.I. radiological study. After a 3 weeks cimetidine treatment and psycho-affective nursing, the ulcer disappeared almost completely. To our knowledge, a stress ulcer occurring in a battered child has not been reported as yet.

Renal sodium-D-glucose cotransport system. Involvement of tyrosine residues in sodium-transporter interaction.

Using brush-border membrane vesicles isolated from calf kidney cortex the effect of tyrosine-reactive reagents on sodium-dependent D-glucose transport was investigated. Treatment of the membranes for 60 min with NBD-Cl (7-chloro-4-nitrobenzo-2-oxa-1,3-diazole), N-acetylimidazole or tetranitromethane decreased D-glucose uptake 50, 70 and 40%, respectively. Tracer exchange experiments revealed that the inhibition of transport is due to a direct modification of the sodium-D-glucose cotransport system. The modification by NBD-Cl decreases the apparent Vmax of the transport system with respect to its interaction with sodium. In addition, the rate of inactivation of the transport system by NBD-Cl is reduced in the presence of high concentrations of sodium. The results indicate that tyrosine residues play an essential role in sodium-D-glucose cotransport and are probably involved in the binding and/or transport of sodium by the sodium-D-glucose cotransport system.