Oxygen radical production in neutrophils interacting with platelets and surface-immobilized plasma proteins: role of tyrosine phosphorylation

The interaction between neutrophil granulocytes and platelets is considered to play an important role in the inflammatory process induced by an implanted foreign material. However, the cellular mechanisms involved remain incompletely understood. We used a luminol-dependent chemiluminescence (CL) technique to analyze the generation of reactive oxygen species (ROS) in human neutrophils interacting with different plasma protein-coated surfaces in the presence or absence of unstimulated or stimulated platelets. The role of tyrosine phosphorylation in the regulation of NADPH oxidase activity was evaluated with quantitative fluorescence microscopy and the specific tyrosine kinase inhibitor genistein. We found that the ROS-production is 2 to 3 times higher in neutrophils on immunoglobulin G (IgG)-coated surfaces than in cells interacting with albumin- or fibrinogen-coated surfaces. Incubation with superoxide dismutase and catalase revealed that about 45% of the ROS was released extracellularly on IgG surfaces whereas corresponding values were 90% and 85% in neutrophils interacting with albumin and fibrinogen, respectively. The presence of platelets markedly increased the extracellular generation of ROS, mainly in neutrophils interacting with IgG- or fibrinogen-coated surfaces whereas the intracellular production was only modestly affected. Quantitative fluorescence microscopy of neutrophils stained with FITC-conjugated anti-phosphotyrosine antibodies showed a correlation between tyrosine phosphorylation, cell spreading, and ROS production. Platelets markedly amplified the anti-phosphotyrosine staining on both fibrinogen- and IgG-coated surfaces whereas the low level of tyrosine phosphorylation in neutrophils on albumin-coated surfaces was not further elevated by platelets. Furthermore, the tyrosine kinase inhibitor genistein inhibited both extra- and intracellular ROS production in neutrophils regardless of the presence of platelets. We demonstrate that plasma protein coating and the presence of platelets are crucial for the inflammatory response of adhering neutrophils and that the oxidative response correlates with the extent of tyrosine phosphorylation of proteins in focal contacts.     

No immunosuppressive effect of transfected annexin II

Annexin II (AXII) was reported to suppress lymphoproliferation and immunoglobulin production. To investigate this further, the AXII-negative human B-lymphoma cell line Raji was transfected with AXII followed by transfection with p11. Stable transfectants were generated. In vitro immunological effects of Raji, Raji-AXII and Raji-AXII-p11 were compared by using irradiated cells as stimulators for PBM in mixed lymphocyte reactions or by adding the supernatants to lymphoproliferation or ELISPOT cultures. None of the assays provided evidence of significant immunosuppression by AXII. Thus, expression of AXII or AXII plus p11 does not by itself give a cell immunosuppressive ability.     

Serum concentrations and effects of gabapentin and vigabatrin: observations from a dose titration study

To explore possible concentration-effect relationships, gabapentin (GBP) and vigabatrin (VGB) serum concentrations were obtained from patients participating in an add-on dose-titration trial comparing GBP and VGB in partial epilepsy. Patients randomized to GBP started on 1800 mg/d and could have their dosage increased stepwise to 2400 and 3600 mg/d if seizures persisted. Those randomised to VGB started on 1000 mg/d, and the dose could be increased to 2000 and 4000 mg/d. Blood samples were obtained at steady state, at a nonstandardized time, from 27 patients randomized to GBP and from 36 randomized to VGB. Serum samples were analyzed using high-performance liquid chromatography. The treatment effect was expressed as percentage reduction in number of seizures from baseline. In addition, patients were classified as responders (>50% reduction in number of seizures from baseline) or nonresponders. There was no significant correlation between serum concentrations of GBP and seizure reduction at the lowest dosage, 1800 mg/d (r = -0.02, P = 0.94, Spearman-rank), nor between VGB serum levels and seizure reduction at 1000 mg/d of VGB (r = -0.14, P = 0.44). The serum GBP concentrations among responders to GBP 1800 mg/d were 26 +/- 12 micro mol/L (mean +/- SD), which was not different from serum concentrations in nonresponders, 28+/-13 micro mol/L. Nor was there a difference between serum concentrations of responders and nonresponders to VGB 1000 mg/d (32 +/- 23 and 44 +/- 36 micro mol/L, respectively). Hence, with the present study design we were unable to identify specific target ranges of GBP and VGB serum concentrations.     

Therapeutic drug monitoring of the newer antiepileptic drugs

The aim of the present review is to discuss the potential value of therapeutic drug monitoring (TDM) of the newer antiepileptic drugs (AEDs) felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine, topiramate, vigabatrin, and zonisamide. Studies of the relationship between serum concentrations and clinical efficacy of these drugs are reviewed, and the potential value of TDM of the drugs is discussed based on their pharmacokinetic properties and mode of action. Analytical methods for the determination of the serum concentrations of these drugs are also briefly described. There are only some prospective data on the serum concentration-effect relationships, and few studies have been designed primarily to study these relationships. As TDM is not widely practiced for the newer AEDs, there are no generally accepted target ranges for any of these drugs, and for most a wide range in serum concentration is associated with clinical efficacy. Furthermore, a considerable overlap in drug concentrations related to toxicity and nonresponse is reported. Nevertheless, the current tentative target ranges for felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine (10-hydroxy-carbazepine metabolite), tiagabine, topiramate, vigabatrin, and zonisamide are 125 to 250 micromol/L, 70 to 120 micromol/L, 10 to 60 micromol/L, 35 to 120 micromol/L, 50 to 140 micomol/L, 50 to 250 nmol/L, 15 to 60 micromol/L, 6 to 278 micromol/L, and 45 to 180 micromol/L, respectively. Further systematic studies designed specifically to evaluate concentration-effect relationships of the new AEDs are urgently needed. Although routine monitoring in general cannot be recommended at present, measurements of some of the drugs is undoubtedly of help with individualization of treatment in selected cases in a particular clinical setting.     

Digital radiography of scoliosis with a scanning method: radiation dose optimization

The aim of this study was optimization of the radiation dose–image quality relationship for a digital scanning method of scoliosis radiography. The examination is performed as a digital multi-image translation scan that is reconstructed to a single image in a workstation. Entrance dose was recorded with thermoluminescent dosimeters placed dorsally on an Alderson phantom. At the same time, kerma area product (KAP) values were recorded. A Monte Carlo calculation of effective dose was also made. Image quality was evaluated with a contrast-detail phantom and Visual Grading. The radiation dose was reduced by lowering the image intensifier entrance dose request, adjusting pulse frequency and scan speed, and by raising tube voltage. The calculated effective dose was reduced from 0.15 to 0.05 mSv with reduction of KAP from 1.07 to 0.25 Gy cm² and entrance dose from 0.90 to 0.21 mGy. The image quality was reduced with the Image Quality Figure going from 52 to 62 and a corresponding reduction in image quality as assessed with Visual Grading. The optimization resulted in a dose reduction to 31% of the original effective dose with an acceptable reduction in image quality considering the intended use of the images for angle measurements. Electronic Publication     

Features indicative of cervical abnormality. A factor to be reckoned with in clinical headache work and research?

The current criteria for cervicogenic headache (CEH) contain an anamnestic and a physical examination part. The latter consists of: 1) range of motion in the cervical spine (1+); 2) mechanical precipitation of head pain (uppermost score: 1.5+). These two factors are included in "Features indicative of cervical abnormality", outlined in the present context, with a view to possibly facilitating CEH diagnosis. These "features" have a wider scope, containing not only the two original factors (1 and 2), but also three additional factors--their relative contribution to the totality also given in parentheses: 3) facet joint tenderness (0.5+); 4) neck muscle tenderness (0.5+); and 5) skin-roll test (1.0+). The sum of the solitary features is, accordingly, 4.5+. An extra 0.5+ can be added if there is extreme positivity of one of the factors, i.e., a maximum of 5.0+. This coarse system concerning cervical function has also been tested out in 1834 parishioners in the V?g? study of headache epidemiology (irrespective of headache diagnoses). The mean number of features increased with increasing intensity of head pain (by a factor of almost 3). In headache-free individuals (n.=246), the mean was 0.42+, against a mean in the whole series of 0.79+. Reproducibility tests demonstrated relatively high consistency.     

A community-based randomized controlled trial of iron and zinc supplementation in Indonesian infants: interactions between iron and zinc

BACKGROUND: Combined supplementation with iron and zinc during infancy may be effective in preventing deficiencies of these micronutrients, but knowledge of their potential interactions when given together is insufficient. OBJECTIVE: The goal was to compare the effect in infants of combined supplementation with iron and zinc and of supplementation with single micronutrients on iron and zinc status. DESIGN: Indonesian infants (n = 680) were randomly assigned to daily supplementation with 10 mg Fe (Fe group), 10 mg Zn (Zn group), 10 mg Fe + 10 mg Zn (Fe+Zn group), or placebo from 6 to 12 mo of age. Venous blood samples were collected at the start and end of the study. Five hundred forty-nine infants completed the supplementation and had both baseline and follow-up blood samples available for analysis. RESULTS: Baseline prevalences of anemia, iron deficiency anemia (anemia and low serum ferritin), and low serum zinc (< 10.7 micromol/L) were 41%, 8%, and 78%, respectively. After supplementation, the Fe group had higher hemoglobin (119.4 compared with 115.3 g/L; P < 0.05) and serum ferritin (46.5 compared with 32.3 microg/L; P < 0.05) values than did the Fe+Zn group, indicating an effect of zinc on iron absorption. The Zn group had higher serum zinc (11.58 compared with 9.06 micromol/L; P < 0.05) than did the placebo group. There was a dose effect on serum ferritin in the Fe and Fe+Zn groups, but at different levels. There was a significant dose effect on serum zinc in the Zn group, whereas no dose effect was found in the Fe+Zn group beyond 7 mg Zn/d. CONCLUSION: Supplementation with iron and zinc was less efficacious than were single supplements in improving iron and zinc status, with evidence of an interaction between iron and zinc when the combined supplement was given.     

3,4-DGE in peritoneal dialysis fluids cannot be found in plasma after infusion into the peritoneal cavity.

OBJECTIVE: Glucose degradation products (GDPs) are important in the outcome of peritoneal dialysis (PD) treatment. 3,4-dideoxyglucosone-3-ene (3,4-DGE) is the most cytotoxic GDP found in conventionally manufactured fluids and may, in addition, be recruited from 3-deoxyglucosone (3-DG). It is not known what happens with those GDPs in patients during PD. The aim of this study was to investigate if the 3,4-DGE and 3-DG in PD fluids can be found in plasma during treatment. DESIGN: PD patients were dialyzed with a conventional PD fluid containing 43 micromol/L 3,4-DGE and 281 micromol/L 3-DG. Parallel experiments were performed in rats as well as in vitro with human plasma. The rats were dialyzed with a PD fluid containing 100 micromol/L 3,4-DGE and 200 micromol/L 3-DG. RESULTS: The concentration of 3,4-DGE in the peritoneum decreased at a much higher rate than 3-DG during the dwell. 3,4-DGE was not, however, detected in the plasma of patients or rats during dialysis. The concentration of 3-DG in plasma peaked shortly after infusion of the fluid to the peritoneal cavity. The concentration of 3,4-DGE during experimental incubation in plasma decreased rapidly, while the concentration of 3-DG decreased only 10% as rapidly or less. CONCLUSION: 3,4-DGE could not be detected in plasma from either PD patients or rats during dialysis. This is presumably due to its high reactivity. 3-DG may, on the other hand, pass through the membrane and be detected in the blood.     

Test atmospheres of diisocyanates with special reference to controlled exposure of humans

Summary An all glass apparatus for the generation of air concentrations of 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI) and 1,6-hexamethylene diisocyanate (HDI) was deveoped. The generation principle was based on gas-phase permeation with permeation membranes of silicon rubber. In an 8 m³ stainless steel test chamber, low and steady TDI- and HDI atmospheres (1-100 μg/m³) could be maintained. The diisocyanate concentrations were determined by an HPLC method, using the 9-(N-methylaminomethyl)-anthracene reagent utilizing UV detection. The sum of diisocyanates and their related amines were determined by sampling in 0.4M hydrochloric acid solution, and analysis by capillary gas chromatography with thermionic specific detection. Related amines were determined by sampling in ethanol — 0.2% KOH and analysis on GC-TSD. A continuous band-tape monitor was used for the determination of diisocyanates. Losses of diisocyanates in the test chamber were evaluated by measuring the TDI and HDI concentrations at the inlet respectively the outlet of the test chamber. At the outlet of the test chamber, ca 25% of the TDI respectively HDI concentrations were recovered. With a male subject in the test chamber ca 15% of the HDI concentration was recovered. The air flow through the test chamber was ca 10 M³ /h. The changes in isomeric composition of airborne TDI, at stopped flow conditions, showed that the decay of the 2,4-isomer was faster than of the 2,6-isomer. No trace of the related amine toluene diamine (TDA) was detected in the test chamber, at TDI concentrations ranging from 20 to 50 μg/m³. Sampling losses due to sampling connections were evaluated. No losses for TDI and HDI were obtained with 150 mm impinger tubings of glass, teflon or stainless steel. Sampling losses ranging from ca 30 to 80% for TDI and ca 35 to 65% for HDI, were caused by tubings of silicone rubber, latex, polypropene and polyvinylchloride.     

Could sound be used as a strategy for reducing symptoms of perceived motion sickness?

Background  

Working while exposed to motions, physically and psychologically affects a person. Traditionally, motion sickness symptom reduction has implied use of medication, which can lead to detrimental effects on performance. Non-pharmaceutical strategies, in turn, often require cognitive and perceptual attention. Hence, for people working in high demand environments where it is impossible to reallocate focus of attention, other strategies are called upon. The aim of the study was to investigate possible impact of a mitigation strategy on perceived motion sickness and psychophysiological responses, based on an artificial sound horizon compared with a non-positioned sound source.