Common antigenic determinants in the glycoproteins of plants,molluscs and insects

An antiserum raised against -fructosidase isolated from the cell walls of suspension-cultured carrot cells cross-reacts with many plant proteins and hemocyanin ofHelix pomatia. The shared epitope appears to be a small complex glycan with a (1–2)-linked xylose residue attached to the -linked mannose residue of the core of an asparagine-linked oligosaccharide. There is strong cross-reactivity with the proteins of many seed plants, molluscs and insects, and no cross-reactivity with the proteins of fungi, algae, mosses, ferns, or any of the vertebrates tested. Xylose-containing glycans appear to increase the immunogenicity of the proteins to which they are attached, and we suggest that they may be responsible for some allergic responses of people that are repeatedly exposed to plant or insect proteins.     

Further evidence for a biological role of anti-estrogen-binding sites in mediating the growth inhibitory action of diphenylmethane derivatives

Several diphenylmethane derivatives have been synthesized with variable affinities for Anti-estrogen Binding Sites (ABS) but not for the estrogen receptor. Using these molecules as probes it is shown that their binding affinities for ABS correlate with their abilities to inhibit the growth of MCF-7 human breast cancer cells. In contrast they have no influence on the proliferation of tamoxifen-resistant variant cells (RTx6) in which ABS are undetectable. These data support the conclusion that ABS has a functional role in the anti-proliferative effect of triphenylethylene anti-estrogens and structurally related compounds.     

Concentrations of Homovanillic Acid and 5-Hydroxyindoleacetic Acid in Cerebrospinal Fluid from Human Infants in the Perinatal Period

To assess maturation of central serotonin and catecholamine pathways at birth, we measured lumbar CSF homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA), stable acid metabolites of dopamine and serotonin, using HPLC with electrochemical detection. CSFs from 57 neonates (38 premature and 19 at term) and 13 infants 1-6 months old were studied. HVA levels increased with maturity (p less than 0.05; ANOVA), whereas 5-HIAA levels were similar in all these subjects. HVA/5-HIAA ratios increased markedly from 1 +/- 0.12 in the most premature neonates to 1.98 +/- 0.17 in the older infants (p less than 0.01; t test). There were no sex differences for these values.     

Influence of auxin and mycorrhizal fungi on thein vitro formation and growth ofPinus pinaster roots

Summary Experiments, performed withPinus pinaster cloned shoots submitted to an auxin treatment (NAA 10^–6 M, 18 days), demonstrated that rooting abilityin vitro persists over 5 successive induction cycles (through out a 9-month period). Rooting ability needs a permanent synthesis of auxin synergists which activate the metabolism of cell dedifferentiation and root primordium initiation. Agar culture permitted intense meristem initiation, but prevented active root elongation. In the presence of a mycorrhizal fungus,Pisolithus tinctorius orHebeloma cylindrosporum, roots resumed growth and short lateral root formation was stimulated. These two phenomena induced by fungal association improve the quality of the root systems required to facilitate successful transplantation from test-tubes to field conditions.     

Methacarn (methanol-Carnoy) fixation

Summary According to chemical data, methanol raises the shrinkage temperature of collagen significantly more than ethanol (86° C versus 70° C). Since increase of shrinkage temperature appears desirable in tissues to be embedded in paraffin, methanol was substituted for ethanol in Carnoy's fluid. This methanol-Carnoy mixture is referred to as methacarn solution. The fixation-embedding procedure was similar to that described in the study of Carnoy fixation. Methacarn-fixed sections showed little or no shrinkage and compared well with material fixed in Carnoy's or Zenker's fluid. Myofibrils, especially in endothelial and epithelial cells, were more prominent in methacarn- than in Carnoy-fixed tissues.A review of the chemical literature showed that methanol, ethanol and chloroform stabilize or even enhance helical conformations of proteins, presumably by strengthening of hydrogen bonds. Interference with hydrophobic bonds causes unfolding and/or structural rearrangements in globular proteins. The twin-helical structure of DNA collapses in alcoholic solutions. Hence, methacarn fixation can be expected to preserve the helical proteins in myofibrils and collagen, but the conformations of globular proteins and DNA will be significantly altered. Literature on conformational effects produced by fixatives used in electron microscopy was also reviewed. Glutaraldehyde and OsO₄ cause considerable loss of helix (22–29% and 39–66% respectively). KMnO₄ and glutaraldehyde followed by OsO₄ produce extensive transitions from helical to random-coil conformations similar to those seen in powerful denaturants such as 8 M urea. Evidently these fixatives are unsuitable for studies of helical proteins. In contrast ethylene glycol preserves helical conformations.     

On the mechanism of sequence iron-hematein stains

Summary As a prerequisite for the histochemical study of sequence iron-hematoxylin stains the iron alum-acidified hematein procedure was developed which does not require differentiation.Histochemical blocking and extraction procedures demonstrated that carboxyl and hydroxyl groups are essential for the binding of cationic iron.The iron alum-Prussian blue reaction colored collagen, reticulum fibers and basement membranes more intensely than muscle fibers. Treatment of tissue sections mordanted in iron alum with the acidified hematein solvent resulted in practically complete removal of iron from all tissue structures. It must therefore be concluded that the selective staining of muscle fibers, terminal bars and related structures with sequence iron-hematein stains is not due to high affinity of iron for these tissue components.Observations by R. and M. Heidenhain on sequence hematoxylin-potassium dichromate and hematoxylin-alum stains and data from modern textile chemistry indicate that the staining patterns obtained with metal-hematein sequence stains are determined by the affinity of the hematein moiety for certain tissue structures.     

Modulation of Histamine Release in the Rat Brain by K-Opioid Receptors

The opioid modulation of histamine release was studied in rat brain slices labeled with L-[3H]histidine. The K(+)-induced [3H]histamine release from cortical slices was progressively inhibited by the preferential kappa-agonists ketocyclazocine, dynorphin A (1-13), Cambridge 20, spiradoline, U50,488H, and U69,593 in increasing concentrations. In contrast, the mu-agonists morphine, morphiceptin, and Tyr-D-Ala-Gly-(NMe)Phe-Gly-ol (DAGO) were ineffective as were the preferential delta-agonists [D-Ala2,D-Leu5]enkephalin (DA-DLE) and [D-Pen2,D-Pen5]enkephalin (DPDPE). Nor-binaltorphimine (nor-BNI) and MR 2266, two preferential kappa-antagonists, reversed the inhibitory effect of the various kappa-agonists more potently than did naloxone, with mean Ki values of 4 nM and 25 nM, respectively. The effects of ketocyclazocine and naloxone also were seen in slices of rat striatum, another brain region known to contain histaminergic nerve endings. We conclude that kappa-opioid receptors, presumably located on histaminergic axons, control histamine release in the brain. However, nor-BNI and naloxone failed, when added alone, to enhance significantly [3H]histamine release from cerebral cortex or striatum, and bestatin, an aminopeptidase inhibitor, failed to decrease K(+)-evoked [3H]histamine release. These two findings suggest that under basal conditions these kappa-opioid receptors are not tonically activated by endogenous dynorphin peptides. The inhibition of cerebral histamine release by kappa-agonists may mediate the sedative actions of these agents in vivo.     

Regulation of Histamine Release and Synthesis in the Brain by Muscarinic Receptors

The cholinergic modulation of histamine release and synthesis was studied in rat brain slices or synaptosomes labeled with L-[3H]histidine. Carbachol in increasing concentrations progressively reduced the K+-induced [3H]histamine release from cortical slices. Pirenzepine, a preferential M1-receptor antagonist, reversed the carbachol effect in an apparently competitive manner and with Ki values of 1-6 X 10(-8) M. 11-[(2-[(Diethylamino)methyl]-1-piperidinyl)acetyl]-5,11-dihydro-6H- pyrido[2,3-b][1,4]benzodiazepine-6-one (AF-DX 116), considered a preferential M2-receptor antagonist, reversed the carbachol effect with a mean Ki of approximately 2 X 10(-7) M. Oxotremorine behaved as a partial agonist in the modulation of histamine release. Neostigmine, an acetylcholinesterase inhibitor, inhibited the K+-induced release of [3H]histamine from cortical slices, and the effect was largely reversed by pirenzepine, an observation suggesting a modulation by endogenous acetylcholine. The effects of carbachol and pirenzepine were observed with slices of other brain regions known to contain histaminergic nerve terminals or perikarya, as well as with cortical synaptosomes. The two drugs also modified, in opposite directions, [3H]histamine formation in depolarized cortical slices. In vivo oxotremorine inhibited [3H]histamine formation in cerebral cortex, and this effect was reversed by scopolamine. When administered alone, scopolamine failed to enhance significantly the 3H- labeled amine formation, a finding suggesting that muscarinic receptors are not activated by endogenous acetylcholine released under basal conditions. It is concluded that muscarinic heteroreceptors, directly located on histaminergic nerve terminals, control release and synthesis of histamine in the brain. These receptors apparently belong to the broad M1-receptor category and may correspond to a receptor subclass displaying a rather high affinity for AF-DX 116.