Antioxidant status in patients with acute respiratory distress syndrome

OBJECTIVES

Reactive oxygen species (ROS) have been implicated in the pathophysiology of ARDS. We investigated the pattern of antioxidants in plasma and ROS production by neutrophils in patients with ARDS over 6 days.

DESIGN

Observational study. Blood samples were taken when the diagnosis was made (D0) and after 3 (D3) and 6 days (D6) during therapy.

SETTING

Intensive care units at a University Hospital.

PATIENTS

Eight patients with ARDS were investigated, 17 healthy volunteers served as controls.

MEASUREMENTS AND RESULTS

Plasma levels of ascorbate, alpha-tocopherol, retinol, beta-carotene, selenium and lipid peroxidation products (MDA) were determined and the activities of the antioxidative enzymes catalase (CAT), superoxide dismutase (SOD) and glutathione-peroxidase (GSH-PX) in erythrocytes were measured. In addition, ROS production (superoxide anion and hydrogen peroxide) in activated neutrophils was assessed. Plasma levels of alpha-tocopherol, ascorbate, beta-carotene and selenium were reduced from the onset of illness. MDA plasma levels were increased throughout the illness. ROS generation from neutrophils was normal on D0 and decreased to D6 in ARDS patients.

CONCLUSION

The antioxidative system is severely compromised in patients with ARDS. Plasma levels of alpha-tocopherol, ascorbate, beta-carotene and selenium are decreased. Elevated MDA levels provide further evidence of massive oxidative stress. The routine replacement of micronutrients according to recommended daily allowances was inadequate to compensate for the increased requirements.

The designer cytokine hyper-interleukin-6 is a potent activator of STAT3-dependent gene transcription in vivo and in vitro

Interleukin-6 (IL-6) triggers pivotal pathways in vivo. The designer protein hyper-IL-6 (H-IL-6) fuses the soluble IL-6 receptor (sIL-6R) through an intermediate linker with IL-6. The intracellular pathways that are triggered by H-IL-6 are not defined yet. Therefore, we studied the molecular mechanisms leading to H-IL-6-dependent gene activation. H-IL-6 stimulates haptoglobin mRNA expression in HepG2 cells, which is transcriptionally mediated as assessed by run-off experiments. The increase in haptoglobin gene transcription correlates with higher nuclear translocation of tyrosine-phosphorylated STAT3 and its DNA binding. As H-IL-6 stimulates STAT3-dependent gene transcription, we compared the molecular mechanism between IL-6 and H-IL-6. Transfection experiments were performed with a STAT3-dependent luciferase construct. The same amount of H-IL-6 stimulated luciferase activity faster, stronger, and for a longer period of time. Dose response experiments showed that a 10-fold lower dose of H-IL-6 stimulated STAT3-dependent gene transcription comparable with the higher amount of IL-6. Cotransfection with the gp80 and/or gp130 receptor revealed that the effect of H-IL-6 on STAT3-dependent gene transcription is restricted to the gp80/gp130 receptor ratio. High amounts of gp130 increased and high amounts of gp80 decreased the effect on H-IL-6-dependent gene transcription. To investigate the in vivo effect of H-IL-6 on gene transcription in the liver, H-IL-6 and IL-6 were injected into C3H mice. H-IL-6 was at least 10-fold more effective in stimulating the DNA binding and nuclear translocation of STAT3, which enhances haptoglobin mRNA and protein expression. Thus H-IL-6 stimulates STAT3-dependent gene transcription in liver cells in vitro and in vivo at least 10-fold more effectively than IL-6. Our results provide evidence that H-IL-6 is a promising designer protein for therapeutic intervention during different pathophysiological conditions also in humans.

Divalent cation block of inward currents and low-affinity K+ uptake in Saccharomyces cerevisiae

We have used the patch clamp technique to characterize whole-cell currents in spheroplasts isolated from a trk1Delta trk2Delta strain of Saccharomyces cerevisiae which lacks high- and moderate-affinity K+ uptake capacity. In solutions in which extracellular divalent cation concentrations were 0.1 mM, cells exhibited a large inward current. This current was not the result of increasing leak between the glass pipette and membrane, as there was no effect on the outward current. The inward current comprised both instantaneous and time-dependent components. The magnitude of the inward current increased with increasing extracellular K+ and negative membrane potential but was insensitive to extracellular anions. Replacing extracellular K+ with Rb+, Cs+, or Na+ only slightly modulated the magnitude of the inward current, whereas replacement with Li+ reduced the inward current by approximately 50%, and tetraethylammonium (TEA+) and choline were relatively impermeant. The inward current was blocked by extracellular Ca2+ and Mg2+ with apparent Kis (at -140 mV) of 363 +/- 78 and 96 +/- 14 microM, respectively. Furthermore, decreasing cytosolic K+ increased the magnitude of the inward current independently of the electrochemical driving force for K+ influx, consistent with regulation of the inward current by cytosolic K+. Uptake of 86Rb+ by intact trk1Delta trk2Delta cells was inhibited by extracellular Ca2+ with a Ki within the range observed for the inward current. Furthermore, increasing extracellular Ca2+ from 0.1 to 20 mM significantly inhibited the growth of these cells. These results are consistent with those of the patch clamp experiments in suggesting that low-affinity uptake of alkali cations in yeast is mediated by a transport system sensitive to divalent cations.

Is speech arrest during wada testing a valid method for determining hemispheric representation of language?

BACKGROUND AND OBJECTIVE

The intracarotid amobarbital procedure, or Wada test, is the method of choice to determine hemispheric representation of language, and is routinely used in the presurgical evaluation for intractable epilepsy. Some investigators perform comprehensive language assessments, but others base language lateralization solely on speech arrest. This study sought to determine whether speech arrest alone during Wada testing provides valid data regarding language lateralization.

METHODS

The subjects (previously reported) were 21 patients evaluated for intractable epilepsy, who underwent language lateralization by Wada testing and functional MRI (FMRI). For each patient, language representation was determined by calculating: (1) a Wada laterality index based exclusively on speech arrest; (2) a Wada laterality index based on comprehensive language assessment; and (3) an FMRI laterality quotient. Correlation coefficients and categorical classifications were analyzed.

RESULTS

There was no significant correlation between the Wada laterality quotient derived from duration of speech arrest and either the comprehensive Wada language laterality score (r =.35, p =.12) or FMRI language laterality score (r =.32, p =.16). Categorical classification as left, right or bilateral language also showed marked discordance between speech arrest and the other two methods.

CONCLUSION

Duration of speech arrest during Wada testing is not a valid measure of language dominance.

[Carcinoid tumors of the lung and asbestos. Clinical aspects for insurance medicine]

Lung dust analyses were performed on tumor-free lung tissue from surgical samples of 28 carcinoid tumors. The measured levels in one surgical sample may easily be correlated with the increased asbestos load of the lung due to the patients' occupation as stone mason. No evidence supporting the correlation of increased chronic asbestos load of the lungs and the development of typical carcinoid tumors of the lung was found.

Use of the restricted academic task in ADHD dose-response relationships

Behavioral assessment techniques have been shown to make a significant contribution in the evaluation of stimulant medication response in children with attention-deficit/hyperactivity disorder. This article examines the role of a behavioral measure consisting of standardized observation of a child while he or she performs an academic-like task (Restricted Academic Task). This technique is reliable and valid for repeated administrations across medication dosages and placebo. It can assist in optimizing medication dosage for individual children, given its sensitivity to dosage effects. It also allows the capture of medication-related changes in an area of functioning that is not directly assessed by parent and teacher judgments and ratings. In this way the Restricted Academic Task may have greater ecological validity than the results of other, more traditional in-clinic measures. Finally, given the idiosyncratic nature of stimulant medication effects on individual children, it contributes to the explication of a specific child's behavioral dose-response relationship.

In vivo and in vitro activities of the gp130-stimulating designer cytokine Hyper-IL-6

IL-6 is a multifactorial cytokine mediating acute inflammatory responses in the liver. When IL-6 binds to a specific receptor (IL-6R), the IL-6/IL-6R complex associates with the signal transducer gp130, initiating intracellular signaling. A soluble form of the IL-6R (sIL-6R) renders target cells sensitive to IL-6 that do not express the IL-6R on their surfaces. A designer cytokine, termed Hyper-IL-6, consisting of IL-6 covalently linked to the sIL-6R was fully active on gp130-expressing cells at 100- to 1000-fold lower concentrations than unlinked IL-6 and IL-6R. Mice were injected i.p. with Hyper-IL-6 or IL-6. Upon injection of Hyper-IL-6 into mice, the acute phase response, as measured by haptoglobin mRNA expression in the liver, was markedly increased and lasted significantly longer compared with that in mice injected with a 10-fold higher dose of IL-6 alone. On human hepatoma cells, Hyper-IL-6 caused similar effects, indicating that the longer lasting response to the fusion protein could not only be explained by the longer plasma half-life of the fusion protein. Experiments using iodinated IL-6 and Hyper-IL-6 revealed that Hyper-IL-6 bound with high affinity to gp130 and was less efficiently internalized. This effect might explain the longer lasting activity of this protein on cells. The highly active IL-6/sIL-6R designer protein might be of significant clinical importance for the stimulation of cells that are more responsive to the IL-6/sIL-6R complex than to IL-6 alone. Such cells include hemopoietic progenitor cells and hepatocytes.

Human IgA- and IgM-secreting intestinal plasma cells carry heavily mutated VH region genes

Single IgA- or IgM-secreting plasma cells were isolated from histological sections of human jejunum and terminal ileum, and Ig heavy chain variable (VH) region genes were amplified and sequenced. Taken together, 62 of 63 cells analyzed harbored somatically mutated VH region genes, indicating that the vast majority of both IgA- and IgM-secreting intestinal plasma cells derive from germinal center B cells. On average, rearranged VH genes of IgA- and IgM-secreting plasma cells showed a mutation frequency of 9.0 % and 8.5 %, respectively, which exceeds the level of somatic mutation of V region genes carried by human memory B cells. Moreover, we detected deletions or insertions in the complementarity-determining regions of 5 of the 58 functional VH region genes analyzed, suggesting that these alterations may contribute to the diversification of the human antibody repertoire in the course of an immune reaction.

A 2-year longitudinal study of swimming navigation in mice devoid of the prion protein: no evidence for neurological anomalies or spatial learning impairments

Uncontrolled accumulation of a conformationally distorted protein (PrP(Sc)) is supposed to be the pathological process leading to spongiform encephalopathy. Targeted disruptions of the Prn-P gene in the mouse have resulted in animals that did not show anomalies in spatial and avoidance learning and were resistant to experimental infections. However, another Prn-P knockout mouse was reported to show ataxia and Purkinje cell degeneration developing after 70 weeks of age. In this study the initial observations are confirmed on swimming navigation of PrP-null mutant mice using an enlarged sample of 58 mice. A representative subsample of 16 mice was then followed up for their ability of swimming navigation up to an age of two years (104 weeks). Surviving PrP-null mutants (n = 4) and controls (n = 6) did not differ in any measure, nor were there indications of ataxia and Purkinje cell degeneration. It was concluded that the PrP-knockout mice used by Büeler et al. were probably normal with respect to aging processes and that resistance to scrapie is not necessarily paid for by late neuronal degeneration. The reasons for the discrepancy between different knockout experiments require experimental clarification, however.

The membrane proximal cytokine receptor domain of the human interleukin-6 receptor is sufficient for ligand binding but not for gp130 association

Interleukin-6 (IL-6) belongs to the family of the "four-helix bundle" cytokines. The extracellular parts of their receptors consist of several Ig- and fibronectin type III-like domains. Characteristic of these receptors is a cytokine-binding module consisting of two such fibronectin domains defined by a set of four conserved cysteines and a tryptophan-serine-X-tryptophan-serine (WSXWS) sequence motif. On target cells, IL-6 binds to a specific IL-6 receptor (IL-6R), and the complex of IL-6.IL-6R associates with the signal transducing protein gp130. The IL-6R consists of three extracellular domains. The NH2-terminal Ig-like domain is not needed for ligand binding and signal initiation. Here we have investigated the properties and functional role of the third membrane proximal domain. The protein can be efficiently expressed in bacteria, and the refolded domain is shown to be sufficient for IL-6 binding. When complexed with IL-6, however, it fails to associate with the gp130 protein. Since the second and the third domain together with IL-6 can bind to gp130 and induce signaling, our data demonstrate the ligand binding function of the third domain and point to an important role of the second domain in complex formation with gp130 and signaling.

[Concentration-dependent changes in the latency and amplitude of somatosensory-evoked potentials by desflurane, isoflurane and sevoflurane]

PURPOSE

Comparison of the influence of desflurane, isoflurane, and sevoflurane on the parameters of cortical somatosensory evoked potentials (SEP).

METHODS

A total of 41 patients were randomly allocated to either the isoflurane, desflurane or sevoflurane group. Following induction with propofol and intubation, concentration of the volatile anaesthetic was kept constant at 1.3, 1.0, and 0.7 MAC for 15 minutes each in randomised sequences. No opioids or N2O were used. Cortical somatosensory evoked potentials were recorded following median nerve stimulation at the wrist with 1.5 times motor threshold current. SEP were evaluated for latencies of peak N20 and P25 as well as peak-to-peak amplitude N20P25. Measurements at the end of the 15 minute equilibration intervals were compared by analysis of variance for repeated measurements. Latencies and the logarithm of the amplitudes were assumed to be normally distributed.

RESULTS

SEP could be recorded in all patients and at all concentrations. Latency of cortical SEP increased with anaesthetic concentration in a linear manner. No differences in latency increase were found between the three anaesthetics (ANOVA). In contrast, the decrease in amplitude with increasing anaesthetic concentration was non-linear. It was large from control to 0.7 MAC, but small in the range between 0.7 and 1.3 MAC. Amplitude reduction was larger with isoflurane than with sevoflurane or desflurane.

CONCLUSION

1) Sevoflurane and desflurane are better suited for anaesthetic management during intraoperative electrophysiological monitoring than isoflurane, because SEP amplitudes are better preserved. 2) SEP amplitude is less altered by changing anaesthetic concentrations in the concentration range from 0.7 to 1.3 MAC than SEP latency.

A randomized controlled trial of early postoperative feeding in gynecologic oncology patients undergoing intra-abdominal surgery

OBJECTIVE

To evaluate the safety and efficacy of early oral feeding after intra-abdominal surgery in gynecologic oncology patients.

METHODS

During a 1-year period, 200 gynecologic oncology patients undergoing intra-abdominal surgery were enrolled in a randomized controlled trial of early compared with traditional oral postoperative feeding. Patients allocated to early postoperative oral feeding began a clear liquid diet on the first postoperative day and then advanced to a regular diet as tolerated. Patients allocated to traditional postoperative oral feeding received nothing by mouth until return of bowel function (defined as the passage of flatus in the absence of vomiting or abdominal distention), then began a clear liquid diet, and advanced to a regular diet as tolerated.

RESULTS

Age, case distribution, surgery length, blood loss, and first passage of flatus were similar in the early and traditional feeding groups. Significantly more patients in the early group developed nausea. Despite this, the incidence of vomiting, abdominal distention, incidence and duration of nasogastric tube use, and percentage of patients who tolerated clear liquid and regular diets on the first attempt were comparable in both groups. Time to development of bowel sounds, time to initiation of clear liquid and regular diets, and hospital stay were significantly longer in the traditional group. Major complications (eg, pneumonia, atelectasis, and wound complications) and febrile morbidity occurred equally in both groups. There were no known anastamotic complications or aspirations in either group. Postoperative changes in hematologic indices and electrolytes were comparable in both groups.

CONCLUSION

Early postoperative feeding in gynecologic oncology patients undergoing intra-abdominal surgery is safe and well tolerated.

Use of intravenous lipids in critically ill patients with sepsis without and with hepatic failure

BACKGROUND

Fat is the preferred energy fuel both in patients with sepsis and with hepatic failure. Thus lipid emulsions should serve as an ideal nutritional substrate in parenteral nutrition. However, previous studies have generated conflicting results on the utilization of artificial lipids in these disease states, and systematic studies in critically ill patients with combined organ dysfunctions and additional complications are lacking. We compared the elimination, hydrolysis, and oxidation of a 20% lipid emulsion in critically ill patients on respiratory support with sepsis and with sepsis plus hepatic failure and in healthy control subjects.

SETTING

Medical critical care unit of a university hospital.

SUBJECTS AND METHODS

Eight critically ill patients with sepsis, 8 patients with sepsis and decompensated chronic hepatic failure, and 10 healthy volunteers were investigated. Elimination and hydrolysis was evaluated during constant i.v. infusion of 4.5 mg.kg body wt-1.min-1 of triglycerides during 120 minutes. Concentrations of plasma triglycerides, free fatty acids, and glycerol were measured, and elimination parameters were analyzed from plasma curves of triglycerides by using a two-compartment model. Resting energy expenditure and substrate oxidation were measured by indirect calorimetry.

RESULTS

In patients with sepsis without and with hepatic failure the rise in plasma triglycerides was blunted and the clearance of triglycerides was enhanced by 20% and 40% (p < .05), respectively, compared with healthy controls. Basal free fatty acid concentrations were elevated, and the rise of free fatty acids and glycerol was comparable to healthy subjects. Energy expenditure was increased and lipid oxidation (as fraction of total energy expenditure) was slightly elevated in both patient groups; the rise in lipid oxidation during lipid infusion was comparable to controls. No side effects or impairment of gas exchange was seen.

CONCLUSIONS

In a clinically relevant dosage range, the utilization of an i.v. lipid emulsion, the elimination and hydrolysis of triglycerides, and the lipid oxidation is not impaired in ventilated critically ill patients with sepsis or sepsis and chronic hepatic failure. Lipid emulsions thus are efficiently metabolized in critically ill patients with combined organ dysfunctions and associated sepsis.

Inhibition of human peripheral blood mononuclear cell proliferation by Streptococcus pyogenes cell extract is associated with arginine deiminase activity

Streptococcus pyogenes (group A Streptococcus) cell extracts (CE) have a remarkably powerful and dose-dependent inhibitory effect on antigen, superantigen, or mitogen-stimulated human peripheral blood mononuclear cell (PBMC) proliferation in vitro. Purification of the inhibitory component present in S. pyogenes type M5 (Manfredo strain) CE by anion-exchange chromatography followed by gel filtration chromatography showed that the inhibitor had an approximate native molecular mass of 100 kDa. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of purified inhibitory fractions followed by silver staining gave a single band with an approximate molecular mass of 47 kDa, indicating that the inhibitor is composed of two identical subunits. NH2-terminal sequencing of the protein revealed that it was identical to the previously characterized streptococcal acid glycoprotein (SAGP); this protein possesses between 31.5 and 39.0% amino acid identity with arginine deiminase (AD) from Mycoplasma hominis, Mycoplasma arginini, Pseudomonas putida, and Pseudomonas aeruginosa. AD enzyme activity was present in unfractionated CE prepared from a range of streptococcal strains, and partially purified inhibitory fractions of Manfredo CE also had high levels of activity. The inhibitory effect of Manfredo CE was overcome by the addition of L-arginine to proliferation assays in which human PBMC were stimulated with phytohemagglutinin. We conclude that SAGP, or its homolog, possesses AD activity and that the potent inhibition of proliferation of human T cells by streptococcal CE is due to activity of this enzyme.

RAPD variation in relation to population size and plant fitness in the rare Gentianella germanica (Gentianaceae)

We investigated the distribution of genetic variation and the relationship between population size and genetic variation in the rare plant Gentianella germanica using RAPD (random amplified polymorphic DNA) profiles. Plants for the analysis were grown from seeds sampled from 72 parent plants in 11 G. germanica populations of different size (40-5000 fruiting individuals). In large populations, seeds were sampled from parents in two spatially distinct subpopulations comparable in area to the total area covered by small populations. Analysis of molecular variance revealed significant genetic variation among populations (P <0.001), while genetic variation among subpopulations was marginally significant (P <0.06). Average molecular variance within subpopulations in large populations did not differ significantly from whole-population values. There was a positive correlation between genetic variation and population size (P <0.01). Genetic variation was also positively correlated with the number of seeds per plant in the field (P <0.02) and the number of flowers per planted seed in a common garden experiment (P <0.051). We conclude that gene flow among natural populations is very limited and that reduced plant fitness in small populations of G. germanica most likely has genetic causes. Management should aim to increase the size of small populations to minimize further loss of genetic variation. Because a large proportion of genetic variation is among populations, even small populations are worth preserving.

Anatomy of lipase binding sites: the scissile fatty acid binding site

Shape and physico-chemical properties of the scissile fatty acid binding sites of six lipases and two serine esterases were analyzed and compared in order to understand the molecular basis of substrate specificity. All eight serine esterases and lipases have similar architecture and catalytic mechanism of ester hydrolysis, but different substrate specificities for the acyl moiety. Lipases and esterases differ in the geometry of their binding sites, lipases have a large, hydrophobic scissile fatty acid binding site, esterases like acetylcholinesterase and bromoperoxidase have a small acyl binding pocket, which fits exactly to their favorite substrates. The lipases were subdivided into three sub-groups: (1) lipases with a hydrophobic, crevice-like binding site located near the protein surface (lipases from Rhizomucor and Rhizopus); (2) lipases with a funnel-like binding site (lipases from Candida antarctica, Pseudomonas and mammalian pancreas and cutinase); and (3) lipases with a tunnel-like binding site (lipase from Candida rugosa). The length of the scissile fatty acid binding site varies considerably among the lipases between 7.8 A in cutinase and 22 A in Candida rugosa and Rhizomucor miehei lipase. Location and properties of the scissile fatty acid binding sites of all lipases of known structure were characterized. Our model also identifies the residues which mediate chain length specificity and thus may guide protein engineering of lipases for changed chain length specificity. The model was supported by published experimental data on the chain length specificity profile of various lipases and on mutants of fungal lipases with changed fatty acid chain length specificity.

Helical superstructures from charged Poly(styrene)-Poly(isocyanodipeptide) block copolymers

Amphiphilic block copolymers containing a poly(styrene) tail and a charged helical poly(isocyanide) headgroup derived from isocyano-L-alanine-L-alanine and isocyano-L-alanine-L-histidine were prepared. Analogous to low-molecular mass surfactants, these block copolymers self-assembled in aqueous systems to form micelles, vesicles, and bilayer aggregates. The morphology of these aggregates can be controlled by variation of the length of the poly(isocyanide) block, the pH, and the anion-headgroup interactions. The chirality of the macromolecules results in the formation of helical superstructures that have a helical sense opposite to that of the constituent block copolymers. The great variety of morphologies displayed by these block copolymers and the fact that they are easily accessible from poly(styrene) and different types of peptides open new opportunities for applications in the fields of life and materials sciences.

Rapid actin-based plasticity in dendritic spines

Dendritic spines have been proposed as primary sites of synaptic plasticity in the brain. Consistent with this hypothesis, spines contain high concentrations of actin, suggesting that they might be motile. To investigate this possibility, we made video recordings from hippocampal neurons expressing actin tagged with green fluorescent protein (GFP-actin). This reagent incorporates into actin-containing structures and allows the visualization of actin dynamics in living neurons. In mature neurons, recordings of GFP fluorescence revealed large actin-dependent changes in dendritic spine shape, similar to those inferred from previous studies using fixed tissues. Visible changes occurred within seconds, suggesting that anatomical plasticity at synapses can be extremely rapid. As well as providing a molecular basis for structural plasticity, the presence of motile actin in dendritic spines implicates the postsynaptic element as a primary site of this phenomenon.

Expression of amino-terminally truncated PrP in the mouse leading to ataxia and specific cerebellar lesions

The physiological role of prion protein (PrP) remains unknown. Mice devoid of PrP develop normally but are resistant to scrapie; introduction of a PrP transgene restores susceptibility to the disease. To identify the regions of PrP necessary for this activity, we prepared PrP knockout mice expressing PrPs with amino-proximal deletions. Surprisingly, PrP lacking residues 32-121 or 32-134, but not with shorter deletions, caused severe ataxia and neuronal death limited to the granular layer of the cerebellum as early as 1-3 months after birth. The defect was completely abolished by introducing one copy of a wild-type PrP gene. We speculate that these truncated PrPs may be nonfunctional and compete with some other molecule with a PrP-like function for a common ligand.