Extracorporeal membrane oxygenation improves coagulopathy in an experimental traumatic hemorrhagic model.

PURPOSE: Hemorrhage is the most common cause of preventable death after trauma. Coagulopathy plays a central role in uncontrolled bleeding and is caused by multiple factors. Extracorporeal Membrane Oxygenation (ECMO) is an established treatment for patients with respiratory failure and has in recent years also been used in severely injured trauma patients with cardiopulmonary failure and coexisting bleeding shock. The aim of this study was to evaluate the effect of ECMO on hypothermia, acidosis, and coagulopathy in a traumatic hemorrhagic rabbit model. METHODS: After anesthesia and tracheostomy, ten New Zealand White rabbits sustained laparotomy, bilateral femur fractures and were hemorrhaged 45% of their estimated blood volume. After 90 min of hemorrhagic shock they were resuscitated with a standard transfusion protocol together with venoarterial ECMO (n = 5) or with a standard transfusion protocol only (n = 5) for 60 min. No systemic heparin was administered. RESULTS: ECMO during 60 min of resuscitation significantly increased heart rate (p = 0.01), mean arterial pressure (p = 0.01), body temperature (p = 0.01) and improved the metabolic acidosis, pH (p = 0.01), and lactate (p = 0.01). ECMO also improved the coagulation capacity measured in vitro by Rotational Thromboelastometry with a significant decrease in clot formation time (p < 0.01). This finding was confirmed in vivo with a significant reduction in the animals' ear bleeding time (p < 0.01) and cuticle bleeding time (p < 0.01); 5/5 animals survived in the ECMO group and 3/5 animals survived in the control group. CONCLUSIONS: Heparin-free ECMO stabilizes circulation, improves coagulation, and may impact short-time survival, during the first 60 min, in an experimental traumatic model with severe hemorrhagic shock.

Circadian amplitude and homeostatic buildup rate in postural control.

Postural control during quiet stance is a common everyday physical activity. Sleepiness is increasingly prevalent in our 24-h society. Yet, little research exists that quantitatively links the fluctuations in sleepiness and postural control. This study quantifies the circadian amplitude and homeostatic buildup rate in postural control. With a force plate we assessed postural control in 12 participants (21-38 years) every 2h during 24h of sustained wakefulness. The sway area was 1.39 ± 0.71 mm(2) at the circadian high around noon, and 4.02 ± 0.67 mm(2) at the circadian low around 6 am (a 189% change, p=0.02). The circadian amplitude of the sway area was therefore 2.63 mm(2). The sway area was 1.92 ± 0.64 mm(2) at the start of the 24-h period and 4.42 ± 0.69 mm(2) at the end of the period (a 130% change, p<0.001). The homeostatic buildup rate of sway area was 0.04 h(-1). The circadian- and homeostatic effects on sway variability, sway velocity, sway frequency and fractal dimension were smaller but still significant. This study found that the circadian amplitude and homeostatic buildup rate are quantifiable from posturographic data, and that they have significant impact on postural control. This finding is important because it means that one could apply the framework of the famous two-process model of sleep regulation (published by Borbély in 1982) to explain the previously reported sleepiness-related changes in postural control.

Quantifying time awake posturographically.

Although sleepiness is a major risk factor in traffic and occupational accidents, convenient, quantitative, and commercial sleepiness testing is lacking. The issue is relevant to policymakers concerned with legislation for, and surveillance of, traffic- and occupational safety. This work suggested and examined posturographic sleepiness testing for instrumentation purposes. In 63 subjects--for whom we tested balance with a force platform during sustained waking for maximum 36 h--sustained waking impaired the balance. The sustained waking explained 60% of the diurnal balance variations, whereas the time of day explained 40% of the balance variations. The first finding -that balance depends on the subject's time awake (TA)- allowed to posturographically estimate the subjects' TA with 86% accuracy and 97% precision. Results also show that balance scores tested at 13:30 hours serve as a threshold to detect excessive sleepiness. This work provides guidelines for a posturographic sleepiness tester.

Model-based posturographic sleepiness monitor tested on 20 subjects.

A previous posturographic force platform study verified that human balance deteriorates as a function of time awake (TA). It found that TA can be estimated with +/-2.5 h accuracy using 30 s trial length. For a fast, reliable and convenient sleepiness monitor even better TA estimation accuracy and shorter trial length is needed. We continued this quest by modeling the quiet stance test situation with a single-link inverted pendulum model (SLIPM). The center-of-mass (COM) trace in the AP (anterior-posterior) direction was calculated from the measured center-of-pressure (COP) trace. The sway angle theta, ankle torque tau and the horizontal force F acting on the COM were calculated from the SLIP equations--each analyzed with 13 different sway measures, i.e. variables that correlate with TA. The effect of circadian rhythm was separated from the sway measures. Twenty subjects' sway measures were analyzed. The SLIPM-based posturographic averaged TA estimation accuracy improved to +/-2.3 h. The trial length could be shortened to 21 s.

Independence of genetic geographical variation between photoperiodic diapause, circadian eclosion rhythm, and Thr-Gly repeat region of the period gene in Drosophila littoralis.

Drosophila littoralis is a latitudinally widespread European species of the Drosophila virilis group. The species has ample genetic variation in photoperiodism (adult diapause) and circadian rhythmicity (pupal eclosion rhythm), with adaptive latitudinal clines in both of them. The possible common genetic basis between the variability of photoperiodism and circadian rhythms was studied by a long-term crossing experiment. A northern strain (65 degrees N) having long critical day length (CDL = 19.9 h) for diapause, early phase of the entrained rhythm in LD 3:21 (psi(LD3:21) = 12.3 h), and short period (tau= 18.8 h) of the free-running rhythm for the eclosion rhythm was crossed with a southern strain (42 degrees N) having short CDL (12.4 h), late eclosion phase (psi(LD3:21) = 20.2 h), and long period (tau= 22.8 h). After 54 generations, including free recombination, artificial selection, and genetic drift, a novel strain resulted, having even more "southern" diapause and more "northern" eclosion rhythm characteristics than found in any of the geographical strains. The observed complete separation of eclosion rhythm characteristics from photoperiodism is a new finding in D. littoralis; in earlier studies followed for 16 generations, the changes had been mostly parallel. Evidently, the genes controlling the variability of the eclosion rhythm and photoperiodism in D. littoralis are different but closely linked. To test for the possible gene loci underlying the observed geographical variability, the period gene was studied in 10 strains covering all the known clock variability in D. littoralis. The authors sequenced the most suspected Thr-Gly region, which is known to take part in the adaptive clock variability in Drosophila melanogaster. No coding differences were found in the strains, showing that this region is not included in the adaptive clock variability in D. littoralis.

Genome homology and superinfection immunity between temperate and virulent Lactobacillus delbrueckii bacteriophages.

The presence of short homologous DNA segments along the genomes of the temperate phage mv4 and the virulent phages LL-H, LL-K and JCL1032 of Lactobacillus delbrueckii was demonstrated with Southern hybridizations. One of these segments, the 2,817 nt MIS element of phage mv4, was further characterized by nucleotide sequence analysis and by superinfection immunity studies.

Repeated sequences and the sites of genome rearrangements in bacteriophages of Lactobacillus delbrueckii subsp. lactis.

We have sequenced the KIS-element, a 1.5 kb insertion segment present in the genome of Lactobacillus delbrueckii subsp. lactis phage LL-K, but absent from its close relative, phage LL-H. The KIS-element showed some sequence features of a transposable element: it was flanked by direct repeats of a 20 nt long sequence which was in the genome of LL-H as a target sequence. The KIS-element contained two putative ORFs. The C-terminal part of ORF333 consisted of clusters of direct repeats, capable of coding Lys/Arg-Gly-Asp motifs, which are known to be able to bind to glycoproteins. A homologous counterpart of the KIS-element was also found in the genome of prolate-headed L. delbrueckii subsp. lactis phage JCL1032, even though the phage JCL1032 is not a close relative of phage LL-K. The nucleotide sequence comparison between KIS-element and its homologous counterpart in JCL1032 showed that there have occurred several genome rearrangements at the repeat clusters.

Characterization of a prolate-headed bacteriophage of Lactobacillus delbrueckii subsp. lactis, and its DNA homology with isometric-headed phages.

A new Lactobacillus delbrueckii subsp. lactis bacteriophage, JCL 1032, was characterized. JCL 1032 had a small, elongated prolate head, and a long non-contractile tail with cross-bars. The restriction map of JCL 1032 genome was constructed with five endonucleases. The genome was 45.8 kb in size, and it had cohesive ends (cos). Molecular masses of the phage structural proteins were also determined. JCL 1032 showed DNA homology with morphologically dissimilar, isometric-headed phages of Lb. delbrueckii (subsp. lactis and subsp. bulgaricus) when analyzed by Southern hybridization. Although in general JCL 1032 was only distantly related to isometric-headed phages, there were also a few short highly homologous (minimal homology 84%) DNA regions.

Upstream activating sequences that are shared by two divergently transcribed operons mediate cAMP-CRP regulation of pilus-adhesin in Escherichia coli.

Transcription of the genes encoding pilus-adhesin of serotype F13 in digalactoside-binding Escherichia coli required activation by the cAMP-CRP complex. Analysis of protein-DNA interaction in vitro showed that CRP bound in a cAMP-dependent manner to a sequence located 0.2 kb upstream of the point of transcription initiation of the pilus subunit operon. The cAMP-CRP activation included, in addition to the main pilus operon, the oppositely oriented operon encoding the Papl regulatory protein. Furthermore, the auto-regulatory product of the promoter-proximal gene (papB) in the pilus subunit operon was found to stimulate the papl transcriptional unit. Thus the cAMP-CRP complex and PapB might act in concert and indirectly promote pili synthesis by stimulating expression of the Papl positive regulator. The results of trans-complementation experiments and analyses using lacZ operon fusion derivatives showed that the cAMP-CRP activation also operated directly in cis on the pilus subunit operon. The region containing the CRP binding site appeared to function as an upstream activating sequence since deletion abolished expression even when the pap regulatory proteins Papl and PapB were supplied in trans. The implications for possible mechanisms of transcriptional activation by the cAMP-CRP complex at this novel location between the two oppositely oriented operons are discussed.

Hypoglycemia in hypopituitary children.

Fifty-two children with growth hormone (GH) deficiency were examined for factors that might influence development of hypoglycemia. Symptomatic and asymptomatic hypoglycemia occurred with equal frequency in children with isolated GH and multiple anterior pituitary deficiencies. Of 52 children, nine (17%) had symptomatic hypoglycemia and 14 (27%) had asymptomatic hypoglycemia. Symptomatic hypoglycemia was more frequent in children who were both young (less than 4 years of age) and lean (elevated height age/weight age [HA/WA] ratio). With HGH therapy, these children had decreases in HA/WA ratios and improvement in carbohydrate homeostasis. Insulin responses to oral glucose and intravenous arginine administration were substantially lowered in children with symptomatic hypoglycemia, A deficiency of gluconeogenic substrate or impairment of amino acid mobilization may be a factor in the development of hypoglycemia in hypopituitarism similar to that postulated for ketotic hypoglycemia.