Affinity Of Substances Research Articles

Expression of neurokinin a receptor mRNA in human nasal mucosa

In airway tissues, it has been suggested that tachykinins act as the transmitter for afferent sensory nerves which respond to various irritants and may be involved in airway allergic reactions. Three classes of tachykinin receptor have been recognized, denoted NK1, NK2 and NK3, which exhibit preferential affinity for substance P, neurokinin A and neurokinin B, respectively. We used molecular probes to study the gene expression and distribution of NK2 receptor in human nasal mucosa. Total RNA was isolated from human nasal mucosa and NK2 receptor mRNA was detected in these tissues using reverse transcriptase polymerase chain reaction (RT-PCR). For an in situ hybridization study of human nasal mucosa, we utilized the PCR directly to incorporate a T7 RNA polymerase promoter sequence onto the NK2 receptor cDNA, and these PCR products were used as the DNA template for producing digoxigenin-labeled antisense and sense RNA probes. These studies revealed that NK2 receptor mRNA was expressed in blood vessels. The results suggest a primary role for neurokinin A in the form of vascular responses in the upper respiratory tract.

Expression of Substance P (NK1) Receptor mRNA in Human Nose

In airway tissues, it has been suggested that substance P is the transmitter of afferent sensory nerves which respond to various irritants and may be involved in airway allergic reactions. Three classes of tachykinin receptor are currently recognized, denoted as NK1, NK2 and NK3, which exhibit preferential affinity for substance P, neurokinin A and neurokinin B, respectively. We used molecular probes to study the gene expression and distribution of NK1 receptor in human nose. Total RNA was isolated from human nasal mucosa and NK1 receptor mRNA was detected in these tissues by using reverse transcription and polymerase chain reaction (RT-PCR). For in situ hybridization study of human nasal mucosa, we utilized the PCR directly to incorporate a T7 RNA polymerase promoter sequence onto the NK1 receptor cDNA, and these PCR products were used as the DNA templates for producing digoxigenin-labelled anti-sense and sense RNA probes. These studies revealed that NK1 receptor mRNA was expressed in submucosal glands and airway epithelium. The results may have an important clinical implication, and also promote further investigation of gene regulation of NK1 receptor in health and disease.

Vincent van Gogh and the Thujone Connection

During his last two years Vincent van Gogh experienced fits with hallucinations that have been attributed to a congenital psychosis. But the artist admitted to episodes of heavy drinking that were amply confirmed by colleagues and there is good evidence to indicate that addiction to absinthe exacerbated his illness. Absinthe was distilled from an alcoholic steep of herbs. Wormwood (Artemisia absinthium) was the most significant constituent because it contributed thujone. This terpene can cause excitation, convulsions that mimic epilepsy, and even permanent brain damage. Statements in van Gogh's letters and from his friends indicate that he had an affinity for substances with a chemical connection to thujone; the documented examples are camphor and pinene. Perhaps he developed an abnormal craving for terpenes, a sort of pica, that would explain his attempts to eat paints and so on, which were previously regarded as unrelated absurdities.

Enzymic inactivation of substance P in the central nervous system.

A membrane-bound 'substance P degrading enzyme' (EC 3.4.24.-) from human brain has been purified to apparent homogeneity. The enzyme was extracted from a membrane fraction of human diencephalon with a non-ionic detergent, Brij 35, and activity was monitored by measuring the rate of disappearance of added substance P using radioimmunoassay, bioassay or radiochemical assay. The enzyme is a thermolabile, neutral metallo-endopeptidase with a relative molecular mass of about 50000. It cleaves substance P between Gln6-Phe7, Phe7-Phe8 and Phe8-Gly9, with a ratio of 0.7:1:1. The breakdown products have been identified by a combination of reverse-phase high-performance liquid chromatography and amino acid analysis. A similar cleavage pattern of substance P has also been demonstrated in a synaptic membrane fraction prepared from rat brain, indicating that a 'substance P-degrading enzyme' is the major peptidase responsible for inactivating the peptide in rat brain membranes. The properties of this enzyme distinguished it from previously described peptidases for which substance P is a substrate. Its high selectivity and its affinity for substance P, among many other neuropeptides, suggest that it may be involved in the physiological inactivation of the peptide by neural tissues.

Korrelation zwischen der Affinität wasserlöslicher Substanzen zu Wolle und ihrer bakteriziden Wirksamkeit

We found that the higher the affinity of a water-soluble substance to wool atpH 7 is the higher as its bactericidal activity. This correlation has now been demonstrated for various chemically differing substances. The said correlation exists separately within the anion-active group and within the cation-active group of substances. Addition of salt increases the affinity of a substance to wool, and simultaneously the bactericidal activity of the said substance is increased. The determination of the affinity of a substance to wool permits to predict the approximate bactericidal (not the bacteriostatic) activity of this substance. We assume that the existence of the said correlation is due to the cystine content of wool.

The Use of adhesive Agents in DDT Sprays

A previous investigation by the writer established that the minimum deposit of DDT on both cement and old painted wood necessary to ensure complete mortality of bed-bugs 48 hours after spraying was 0·2 mg. per sq. cm., and that the toxicity of both surfaces diminished slowly over a period of six months. The present work has shown that when DDT is applied with an adhesive agent, the minimum deposit of insecticide necessary on these surfaces to yield a similar kill at the same interval after treatment was only 0·06 mg. per sq. cm. The addition of an adhesive agent to a DDT spray thus effects considerable economy in the use of DDT. Campbell and West (1944), investigating the toxicity to houseflies of coumarine resin and DDT dissolved in white spirit, have reported an increase in the efficiency of DDT when sprayed with an adhesive agent. These authors confined their investigation to a resin only and they suggested that the coumarone resin conferred, in a manner not specified, increased insecticidal activity on the DDT. The present work has shown that relatively small doses of DDT are highly effective in the presence of at least three dissimilar adhesive agents. It is possible, therefore, that instead of increasing the activity of DDT, the agent merely blocks the minute pores of the treated surface, and by minimising absorption of the solution, increases the amount of DDT available to the insect. Alternatively, the adhesive agent may have some affinity for substances on the surface of the bug's tarsi and so assist transfer of DDT from the sprayed surface to the insect.The residual toxicity of cement treated with DDT and an adhesive agent, like that of a similar surface treated with DDT alone, diminished slowly. The toxicity of painted wood, on the other hand, treated with doses of DDT and adhesive agent ranging from 0·005 to 0·02 mg. per sq. cm., decreased within one month, irrespective of the adhesive agent used. This fall in toxicity is puzzling, particularly in view of the fact that no such decrease occurred when the surface was treated with a heavier deposit of DDT and adhesive agent, namely 0·06 mg. of each per sq. cm. This latter observation seems to preclude a possible interference with the efficiency of DDT by a slow interaction of the paint constituents and the adhesive agent.The application of these adhesive agents, even in relatively high doses, failed to prevent the removal of DDT from a smooth surface by repeated washing and rubbing; furthermore, an increase in the deposit of adhesive agent does not markedly increase the insecticidal efficiency of a given deposit of DDT.

Researches in electricity, seventeenth series: on the source of power in the voltaic pile

In this series, the author continues his experimental investigation of the origin of electric force in the voltaic pile. Having found abundant reason, in the experiments already described, to believe that the electricity of the pile has its origin in the chemical force of the acting bodies, he proceeds to examine how the circumstances which can affect the affinity of substances for each other, influence their power of roducing electric currents. First, with relation to heat :—circuits were made of a single metal and a single fluid, and these were examined with a view to ascertain whether, by applying heat at one of the junctions, only thermo-currents can be produced. Some peculiar effects of heat are noticed and explained; and several very necessary precautions in conducting these experiments are pointed out; and it is found, when these are taken, that heat has a decided and distinct effect over the chemical affinities of the parts of a circuit subjected to its power, and a corresponding influence on the electric current produced. This proceeds to such an extent, that, in some cases, either of two metals can be made positive or negative with respect to the other in the same fluid, solely by virtue of this power of heat. The effect of dilution is then examined. For this purpose, only one metal and one fluid are used in a circuit; but the fluid is rendered more dilute at one point of contact than at the other. It was ascertained that such dilution produces little or no effect with metals which are not acted on by the electrolyte employed; and the precautions requisite as to other points are then stated. But when these are observed, still dilution is found to have a most powerful influence on the results; and, as the author believes, solely on account of its influence on the active chemical affinity. Thus copper in dilute nitric acid is positive with respect to copper in strong nitric acid; and the same is the case with lead, silver, and other metals. It is not that the piece in the weakest acid is always positive with respect to that in the stronger acid; for, in the first place, some very curious cases are given, in which a piece of metal in acid of a certain strength is positive with respect to a piece of the same metal in acid, either stronger or weaker; and, in the next place, other cases are stated in which the piece in the medium acid is negative with respect to the other piece in either stronger or weaker acid. The effect of dilution in nitric acid is such, that when certain different metals are compared together, either can, at pleasure, be made positive or negative with respect to the other; thus, of the five metals, silver, copper, iron, lead, and tin, any one of them can be made either positive or negative with respect to any other; with the sole exception of silver, which is always positive with respect to copper. The inconsistency of these results with any theory of contact electromotive force is then strongly insisted on by the author.