Temperature experiments on nerve and muscle membranes of frogs

The influence of temperature changes in the range of 25°C to –6°C on the time constants of Na activation (m) and inactivation (h) was studied in twitch muscle fibers and the node of Ranvier under voltage-clamp conditions. Arrhenius plots of m and h exhibit a change in activation enthalpy at temperatures below 10°C. Cooling and subsequent heating induce a hystersis in the temperature dependence of m and h Ni²⁺ and UO ₂ ²⁺ increase the hysteresis width. With fast temperature changes the gating kinetics relax to their new values more slowly than the temperature change. Hence, temperature must be changed more slowly than 5°C/min if an additional apparent hysteresis due simply to this relaxation is to be avoided. The data are explained by the hypothesis of a phase transition in the membrane lipids. This conception is favoured over a temperature-induced change in protein conformation, since the neutral local anaesthetic benzocaine shows use-dependent block as if low temperature restricted the access of the drug through the lipid phase to its receptor.Supported by grant NS 08174 from the U.S. Public Health Service and SFB 38 from Deutsche Forschungsgemeinschaft     

Chain mobility in solid polyelectrolyte complexes

²H NMR is used to study the mobility of the alkylene chain in solid poly[(dimethyliminio)-alkylene]s (α,ω-ionenes) complexed with poly(styrenesulfonate). In 10, 10-ionene the alkylene chain motion was probed on samples selectively deuterated at the 1-, 2-, and 4-position as well as in the methyl part of the quaternary ammonium groups. ²H NMR spectra show that all positions in the polymethylene chains are involved in conformational jumps between trans and gauche states. The mobility of the methylene units adjacent to charged centres was found to be significantly reduced compared with that of units in the inner part of the chain. The charged quaternary ammonium groups themselves, however, do not take part in trans-gauche isomerization. An increase in mobility resulting from increasing the length of the alkylene chains between the charge centres was observed in 3,3-, 6,6- and 10,10-ionene complexes labelled in the 2-position. The differences in chain dynamics were also detected via EPR line shapes of small spin probe molecules incorporated into the complexes.     

Hematopoietic progenitor cells and cellular microenvironment: behavioral and molecular changes upon interaction

Cell-cell contact between stem cells and cellular determinants of the microenvironment plays an essential role in controlling cell division. Using human hematopoietic progenitor cells (CD34+/CD38-) and a stroma cell line (AFT024) as a model, we have studied the initial behavioral and molecular sequel of this interaction. Time-lapse microscopy showed that CD34+/CD38- cells actively migrated toward and sought contact with stroma cells and 30% of them adhered firmly to AFT024 stroma through the uropod. CD44 and CD34 are colocalized at the site of contact. Gene expression profiles of CD34+/CD38- cells upon cultivation with or without stroma for 16, 20, 48, or 72 hours were analyzed using our human genome cDNA microarray. Chk1, egr1, and cxcl2 were among the first genes upregulated within 16 hours. Genes with the highest upregulation throughout the time course included tubulin genes, ezrin, c1qr1, fos, pcna, mcm6, ung, and dnmt1, genes that play an essential role in reorganization of the cytoskeleton system, stabilization of DNA, and methylation patterns. Our results demonstrate directed migration of CD34+/CD38- cells toward AFT024 and adhesion through the uropod and that upon interaction with supportive stroma, reorganization of the cytoskeleton system, regulation of cell division, and maintenance of genetic stability represent the most essential steps.     

Zur Bestimmung des Kaliumspiegels im Blutplasma

Zusammenfassung Die Kaliumkonzentration im Blutserum nach der Gerinnung ist höher als im Blutplasma, dessen Gerinnung durch Heparin, Äthylendiamintetraessigsäure (EDTA) oder Citrat verhindert wurde. Die Differenz beträgt beim Hund 15–20%, beim Menschen 12–16% und beim Rind 8–10%.Der Unterschied wird durch den bei der Gerinnung des Blutes auftretenden Zerfall der Thrombocyten hervorgerufen, deren Kaliumgehalt überraschend hoch ist (mindestens das 10–20fache der Konzentration im Plasma).Aus diesem Grund geben Kaliumbestimmungen im Serum, bei denen das Blut während der Präparation der Proben gerinnt, zu hohe Werte gegenüber der tatsächlich in vivo herrschenden Konzentration im Plasma. Messungen der Kaliumkonzentration sollten immer im Plasma erfolgen, wobei als gerinnungshemmende Substanzen Heparin oder EDTA geeignet sind.     

Functional Thin Polymer Films at High Pressure

Summary: A new thin‐film characterization setup was created based on the combination of a surface plasmon spectrometer with an electrochemical cell operated under high pressure of up to 200 MPa and at temperatures up to 120 °C. The examples given to document its performance include photoisomerization studies with poly(methyl methacrylate) (PMMA) films partly derivatized with disperse red (DR1), as well as, a preliminary account of the electropolymerization of EDOT under pressure and the assessment of the redox properties of the resulting thin PEDOT films.

Sketch of the high‐pressure electrochemistry surface plasmon cell.     

Clara cell protein 16 (CC16) gene polymorphism influences the degree of airway responsiveness in asthmatic children

BACKGROUND: Several studies have indicated linkage of chromosome 11q12-13 to asthma and associated traits. Among other candidate genes, the Clara cell protein 16 (CC16) gene maps to this region. CC16 is expressed in the bronchial epithelium and exhibits potent anti-inflammatory properties. A single-nucleotide polymorphism (SNP) in the CC16 gene (A38G) was previously associated with asthma. OBJECTIVE: We evaluated the role of the CC16 SNP in pediatric asthma and asthma severity in 2 German study populations. METHODS: The German Multicenter Allergy Study (MAS) cohort (n = 872, 94 asthmatic patients) and 112 allergic asthmatic children recruited in Freiburg, Germany, were included in the present study. Histamine provocations were performed at the age of 7 years in the MAS cohort to determine bronchial hyperreactivity; in the Freiburg study population a standardized exercise-induced decrease in FEV1 was evaluated. For genotyping, melting-curve analysis and restriction enzyme digestion were applied. RESULTS: No association of the CC16*38A allele with asthma could be observed in either study population. However, in asthmatic subjects (MAS cohort) PC(20)FEV(1) values were significantly lower in individuals homozygous or heterozygous for the CC16*38A allele compared with those in subjects with the CC16*38GG genotype (P <.05 and P <.03, respectively). Similarly, allergic asthmatic patients in the Freiburg cohort showed a significantly greater decrease in FEV1 after exercise when homozygous for the CC16*38A allele compared with that seen in asthmatic patients with the *38AG or *38GG genotype (P <.04 and P =.006, respectively). CONCLUSION: We conclude that the CC16*A38G SNP influences bronchial hyperreactivity and might be a genetic determinant of asthma severity in German children.     

Laser microdissection and pressure catapulting (LMPC) in paraffin sections mounted on glass slides. A methodological report

The technique of laser microdissection together with laser pressure catapulting (LMPC) is demonstrated in paraffin sections obtained from surgical specimens of brain tumors mounted on glass slides. A sufficient and precise application of microdissection techniques in tissue on glass slides is worthwhile, since it offers the possibility of a retrospective analysis of archived paraffin sections in histopathology. We could demonstrate a precise dissection of areas in tissues of different thicknesses (4 microm and 20 microm). Areas of tissue mounted directly on glass need to be dissected in a scanning mode in order to remove the total region in form of small tissue fragments row by row. This mode provided a precise microdissection of tissue areas of different sizes and shapes. A successful molecular biological analysis of the microdissected regions could be demonstrated. As an example for such an analysis, differential-PCR for detecting an amplification of the gene for the epidermal growth factor receptor (EGFR) was performed.     

Neuronal apoptosis in the dentate gyrus in humans with subarachnoid hemorrhage and cerebral hypoxia

Apoptosis of dentate granule cells is a typical feature of several animal models of disease. In 20 autopsy cases of subarachnoid hemorrhage (SAH) and global cerebral hypoxia caused by protracted shock or respiratory failure, we evaluated by light microscopy and in situ tailing whether this pattern of neuronal damage also occurs in humans. In subarachnoid hemorrhage, 4.0/mm2 (0-13.0/mm2) apoptotic neurons were observed in the dentate gyrus, in cerebral hypoxia 3.6/mm2 (0-19.9/mm2) (p>0.05), and in 10 aged-matched control cases dying rapidly from non-neurological diseases 0/mm2 (0-0/mm2) (median [range]) (p<0.001 versus SAH and hypoxia). Neuronal apoptosis in the dentate gyrus was most frequent, when death occurred later than 24 hours and less than 11 days after disease onset. Neuronal damage in the hippocampus was always necrotic. It was more severe in hypoxia than in SAH (median neuronal damage score 3 [range: 0-3] versus 0 [0-3], p<0.001). Apoptosis appears to be the predominant mechanism of death in dentate granule cells irrespective of the underlying disease, whereas neuronal death in the hippocampus generally is of necrotic morphology.     

The effect of anti-IgE treatment on in vitro leukotriene release in children with seasonal allergic rhinitis

BACKGROUND: Binding of allergens with IgE to the IgE receptors on mast cells and basophils results in the release of inflammatory mediators as sulfidoleukotrienes (SLTs), triggering allergic cascades that result in allergic symptoms, such as asthma and rhinitis. OBJECTIVE: We sought to investigate whether anti-IgE (Oma-lizumab), a humanized monoclonal anti-IgE antibody, in addition to specific immunotherapy (SIT) affects the leukotriene pathway. METHODS: Ninety-two children (age range, 6-17 years) with sensitization to birch and grass pollens and with seasonal allergic rhinitis were included in a phase III, placebo- controlled, multicenter clinical study. All subjects were randomized to one of 4 treatment groups. Two groups subcutaneously received birch SIT and 2 groups received grass SIT for at least 14 weeks before the start of the birch pollen season. After 12 weeks of SIT titration, placebo or anti-IgE was added for 24 weeks. The primary clinical efficacy variable was symptom load (ie, the sum of daily symptom severity score and rescue medication score during pollen season). Blood samples taken at baseline and at the end of study treatment after the grass pollen season were used for separation of leukocytes in this substudy. After in vitro stimulation of the blood cells with grass and birch pollen allergens, SLT release (LTC4, LTD4, and LTE4) was quantified by using the ELISA technique. RESULTS: Before the study treatment, SLT release to birch and grass pollen exposure did not differ significantly among the 4 groups. Under treatment with anti-IgE + SIT-grass (n = 23), a lower symptom load occurred during the pollen season compared to placebo + SIT-grass (n = 24, P =.012). The same applied to both groups receiving birch SIT (n = 23 and n = 22, respectively; P =.03). At the end of treatment, the combination of anti-IgE plus grass SIT, as well as anti-IgE plus birch SIT, resulted in significantly lower SLT release after stimulation with the corresponding allergen (416 ng/L [5th-95th percentile, 1-1168] and 207 ng/L [1-860 ng/L], respectively) compared with placebo plus SIT (2490 ng/L [384-6587 ng/L], P =.001; 2489 ng/L [1-5670 ng/L], P =.001). In addition, treatment with anti-IgE was also followed by significantly lower SLT releases to the allergens unrelated to SIT (grass SIT: 300 ng/L [1-2432 ng/L] in response to birch allergen; birch SIT: 1478 ng/L [1-4593 ng/L] in response to grass pollen) in comparison with placebo (grass SIT: 1850 ng/L [1-5499 ng/L], P =.001; birch SIT: 2792 ng/L [154-5839 ng/L], P =.04]. CONCLUSION: Anti-IgE therapy reduces leukotriene release of peripheral leukocytes stimulated with allergen in children with allergic rhinitis undergoing allergen immunotherapy independent of the type of SIT allergen used.