Effect of urethan anesthesia on cigarette smoke-induced airway injury in guinea pigs

The effect of urethan anesthesia on cigarette smoke-induced airway responsiveness and permeability was studied in the guinea pig. Airway responsiveness was determined by measuring changes to airway resistance to graded doses of aerosolized histamine, and mucosal permeability was determined by measuring the appearance of fluorescein isothiocyanate-dextran (FITC-D) in the blood and examining its distribution in lung tissue after it had been delivered to the lung in an aerosol. The results confirm previous studies that smoke exposure increased airway responsiveness and mucosal permeability. They also show that urethan anesthesia administered before smoke exposure prevented the smoke-related changes in airway reactivity and mucosal permeability. In animals that remained conscious during the smoke exposure, there was increased deposition of the dextran in the regions of the bronchioloalveolar junctions with a more rapid uptake of FITC-D into the blood. We postulate that, when urethan anesthesia is administered before smoke exposure, the exudative phase of the inflammatory reaction produced by smoke exposure is suppressed.     

Influence of carbohydrate side chains on activity of tissue-type plasminogen activator

When messenger RNA (mRNA) from both untreated and phorbol ester-treated melanoma cells is translated in simple reticulocyte lysates, tissue-type plasminogen activator can be immunoprecipitated by an affinity-purified antibody as a approximately 52,000 mol wt protein, with no detectable biological (plasminogen activating) activity. When the reticulocyte lysate system is supplemented with a preparation of microsomal membranes, biological activity becomes detectable and a 63,000 mol wt protein can be immunoprecipitated with the same antibody. Furthermore, when natural tissue-type plasminogen activator (mol wt approximately equal to 70,000) is incubated with different glycosidases, distinct alterations in the electrophoretic mobility of the molecules are observed, together with alterations in the level of biological activity. While treatment with neuraminidase and beta-galactosidase caused decreases in activity, alpha-mannosidase caused an increase. These results suggest that the carbohydrate part of the molecule can influence its biological behavior.     

Avidin-HRP conjugates in biotin-avidin immunoenzyme cytochemistry

Avidin-HRP conjugates were prepared, analysed and tested for avidin-biotin immunocytochemistry. Suitable biotinylation of enzymes, antigens and antibody was obtained by reacting biotin at equimolar ratio to epsilon aminogroups in proteins. The avidin-biotin interaction was used for immunocytochemical detection of phenomena in the field of immunology, i.e. immune complex trapping, specific antibody forming cells and in serology for the cytochemical detection of human auto-antibodies to basement membrane components. Avidin-HRP conjugation using the two step glutaraldehyde method gave a very small amount of monomeric, low molecular weight conjugate with excellent performance. Avidin-HRP conjugation using the periodate method was modified at two points. The first modification concerns the molar ratio of avidin to HRP in the reaction mixture which was brought to about equimolarity. The second modification concerns the periodate concentration which was decreased five fold, ten fold and twenty fold. Decreasing the periodate concentration decreased the amount of polymeric conjugate. Optimal amounts of monomeric, low molecular weight conjugate were obtained with a ten fold decrease of the periodate concentration. Comparable cytochemical results were obtained with monomeric conjugates obtained using both preparation methods.     

Construction of fifteen human chromosome-specific DNA libraries from flow-purified chromosomes

We report the construction of 15 human chromosome-specific DNA libraries. Metaphase chromosomes were purified by flow sorting and the DNA was extracted and cleaved with HindIII before cloning into the lambda vector Charon 21A. A sensitive miniblot hybridization method was used to monitor the physical and biochemical steps in the cloning procedure. Using this method, we have developed a highly efficient protocol for producing large numbers of recombinant phage from 0.2-1.0 X 10(6) sorted chromosomes. DNA from the following chromosomes was cloned: #4, 6, 8, 9, 11, 13, 14 + 15, 16, 17, 18, 19, 20, 21, 22 and Y. These libraries are available to the scientific research community and will be valuable in the genetic analysis of the human genome.     

8q24.12 Interstitial deletion in trichorhinophalangeal syndrome type I

Summary In the present report we present the first example of a small interstitial 8q24.12 deletion in a patient with trichorhinophalangeal syndrome type I.     

5-hydroxytryptamine and precapillary vessels

The complexity of the vascular effects of 5-hydroxytryptamine (5-HT) is illustrated by differences in sensitivity to the amine among arterial tissues of different origin. The interaction of 5-HT with 5-HT2 receptors is inhibited by specific antagonists such as ketanserin and methysergide. Such compounds also inhibit the contractile responses to endogenous 5-HT released from aggregating platelets. The vasodilator component of the response to 5-HT can be unmasked in the presence of serotonergic blockade, provided the antagonist used has no partial agonistic properties. 5-HT augments (amplifies) the vasoconstrictor responses to adrenergic and nonadrenergic neurohumoral mediators. The amplifying effect of the monoamine is prevented by 5-HT2-serotonergic antagonists such as ketanserin.     

A sensitive cyclic nucleotide phosphodiesterase assay for transient enzyme kinetics

A rapid and sensitive method was developed for the quantitative determination of alpha-tocopherol in tissues and plasma of rats and mice. Tissue and plasma were extracted in acetone and chromatographed on a reverse-phase C18 column with 2% water in methanol. Fluorescence and ultraviolet detection were used for tissue and plasma alpha-tocopherol levels, respectively. Extraction of tissues and plasma was found to be more complete in acetone than in other solvent systems analyzed. The average recovery of alpha-tocopherol added to tissue samples was 97%. As little as 0.1 g of tissue or 0.1 ml plasma can be accurately used for analysis. The method is sensitive to 0.05 micrograms alpha-tocopherol/g tissue.     

Temperature- and structure-dependent interaction of pyrethroids with the sodium channels in frog node of Ranvier

(1) The interaction of a series of pyrethroid insecticides with the Na+ channels in myelinated nerve fibres of the clawed frog, Xenopus laevis, was investigated using the voltage clamp technique. (2) Out of 11 pyrethroids 9 insecticidally active compounds induce a slowly decaying Na+ tail current on termination of a step depolarization, whereas the Na+ current during depolarization was hardly affected. These tail currents are most readily explained by a selective reduction of the rate of closing of the activation gate in a fraction of the Na+ channels that have opened during depolarization. (3) The rate of decay of the Na+ tail current varies considerably with pyrethroid structure. After alpha-cyano pyrethroids the decay is at least one order of magnitude slower than after non-cyano pyrethroids. The decay always follows a single-exponential time course and is reversibly slowed when the temperature is lowered from 25 to 0 degrees C. Arrhenius plots in this temperature range are linear. (4) These results indicate that the relaxation of the activation gate in pyrethroid-affected Na+ channels is governed by an apparent first order, unimolecular process and that the rate of relaxation is limited by a single energy barrier. Application of transition state theory shows that after alpha-cyano pyrethroids this energy barrier is 9.6 kJ/mol higher than after non-cyano pyrethroids. (5) Differences in rate of decay of the Na+ tail current account for the reported differences in repetitive nerve activity induced by various pyrethroids. In addition, the effect of temperature on the rate of decay explains the increase in repetitive activity with cooling.     

Role of pit membranes in macromolecule-induced wilt of plants

Macromolecules present in low concentrations in xylem fluid of Medicago sativa L. var DuPuits will increase the resistance to xylem liquid flow. This increase in resistance was found to be reversible by backflushing the xylem. Autoradiography showed that very large molecules do not pass through pit membrane pores. A comparison of pit membrane pore sizes to molecule sizes suggests that increased resistance to xylem flow is a result of plugging pit membrane pores. It was also found that pit membranes located in two parts of the plant differ in the apparent diameter of their pores and, thus, in their susceptibility to plugging by macromolecules. Macromolecules in xylem fluid may result from hostparasite interactions and may play a significant role in the outcome of the interaction.