LYSOSOMES IN THE RAT SCIATIC NERVE FOLLOWING CRUSH

Peripheral nerves undergoing degeneration are favorable material for studying the types, origins, and functions of lysosomes. The following lysosomes are described: (a) Autophagic vacuoles in altered Schwann cells. Within these vacuoles the myelin and much of the axoplasm which it encloses in the normal nerve are degraded (Wallerian degeneration). The delimiting membranes of the vacuoles apparently form from myelin lamellae. Considered as possible sources of their acid phosphatase are Golgi vesicles (primary lysosomes), lysosomes of the dense body type, and the endoplasmic reticulum which lies close to the vacuoles. (b) Membranous bodies that accumulate focally in myelinated fibers in a zone extending 2 to 3 mm distal to the crush. These appear to arise from the endoplasmic reticulum in which demonstrable acid phosphatase activity increases markedly within 2 hours after the nerve is crushed. (c) Autophagic vacuoles in the axoplasm of fibers proximal to the crush. The breakdown of organelles within these vacuoles may have significance for the reorganization of the axoplasm preparatory to regeneration. (d) Phagocytic vacuoles of altered Schwann cells. As myelin degeneration begins, some axoplasm is exposed. This is apparently engulfed by the filopodia of the Schwann cells, and degraded within the phagocytic vacuoles thus formed. (e) Multivesicular bodies in the axoplasm of myelinated fibers. These are generally seen near the nodes of Ranvier.     

Barbiturate Mortality as an Index of Barbiturate Use,Canada, 1950-1963

Changes in Canadian rates of mortality from barbiturates are examined, and their relation to barbiturate use in the general population is discussed. While the number of deaths attributed to barbiturates quadrupled, from 63 in 1950 to 232 in 1963, there has been a concomitant decrease in the number of deaths from inhalation of utility gas.Combined rates for deaths from utility gas and barbiturates declined steadily for most age groups between 1950-52, 1955-57, and 1959-63. It is possible that the increased mortality from barbiturates represents a change in fashion in regard to method of suicide. Changed mortality from barbiturates is not a valid measure of the extent to which consumption of barbiturates has increased in the Canadian population.     

β-Dl-Methylene-aspartate,an inhibitor of aspartate aminotransferase,potently inhibitsl-glutamate uptake into astrocytes

[³H]Glutamate uptake into astrocytes in primary culture was potently inhibited by the aspartate analoguesl- andd-aspartic acid,Dl-threo--hydroxy-aspartic acid,l-aspartic acid--hydroxymate (IC50's: 136, 259, 168, and 560 M, respectively) and by -Dl-methylene-aspartate, a suicide inhibitor of asparate aminotransferase (IC50: 524 M), and by the endogenous sulphur-containing amino acidl-cysteinesulfinic acid (IC50: 114 M). [³H]Glutamate uptake was not significantly affected by either N-methyl-d-aspartate orDl-homocysteine thiolactone. These results demonstrate that other excitatory amino acids including aspartate andl-cysteinesulfinic acid (but excludingl-homocysteic acid) interact with the glutamate transport system of astrocytes. Inhibition of glutamate uptake may significantly increase the level of neuronal excitability.     

Degradation of some phenols and hydroxybenzoates by the imperfect ascomycetous yeastsCandida parapsilosis andArxula adeninivorans: evidence for an operative gentisate pathway

The imperfect ascomycetous yeastsCandida parapsilosis andArxula adeninivorans degraded 3-hydroxybenzoic acid via gentisate which was the cleavage substrate. 4-Hydroxybenzoic acid was metabolized via protocatechuate. No cleavage enzyme for the latter was detected. In stead of this NADH- and NADPH-dependent monooxygenases were present. In cells grown at the expense of hydroquinone and 4-hydroxygenzoic acid, enzymes of the hydroxyhydroquinone variant of the 3-oxoadipate pathway were demonstrated, which also took part in the degradation of 2,4-dihydroxybenzoic acid byC. parapsilosis.Abbreviations HHQ Hydroxyhydroquinone (1,2,4-trihydroxybenzene) - GSH reduced Glutathione     

Cell-cell interactions influence oligosaccharide modifications on mucins and other large glycoproteins

Intratumoral phenotypic diversity is well documented with regard to tumor associated carbohydrate antigens (TACA). The factors which control the expression of these cell-surface oligosaccharides on different cells of the same tumor are not understood. We investigated the expression of a panel of mucin associated oligosaccharides in cell lines growing at different surface densities (number of cells per cm² of growth flask). Results show that the apparent expression of extended Le^a-Le^x, Le^a and Le^x, sialyl Le^a, Tn and sialyl Tn varies with density of growth by an invasive human squamous cell lung carcinoma cell line (NU6-1), a benign variant (NE-18) and the human lung epithelial cell line BEAS-2B. The results indicate that one of the factors influencing the apparent expression of mucin-associated oligosaccharides is cell-cell interactions.Abbreviations Mab monoclonal antibody - FIT fluorescein isothiocyanate - TACA tumor associated carbohydrate antigen     

Isolation of an anaerobic bacterium which reductively dechlorinates tetrachloroethene and trichloroethene

Strain TEA, a strictly anaerobic, motile rod with one to four lateral flagella and a crystalline surface layer was isolated from a mixed culture that completely reduces chlorinated ethenes to ethene. The organism coupled reductive dehalogenation of tetrachloroethene or trichloroethene to cis-1,2-dichloroethene to growth, using molecular hydrogen as the electron donor. It was unable to grow fermentatively or in the presence of tri- or tetrachloroethene with glucose, pyruvate, lactate, acetate or formate. The 16S rDNA sequence of strain TEA was 99.7% identical to that of Dehalobacter restrictus. The two organisms thus are representatives of the same species or the same genus within the Bacillus/Clostridium subphylum of the gram-positive bacteria.     

Synthesis and lodination of human (phenylalanine13, tyrosine19) melanin-concentrating hormone for radioreceptor assay

An analogue of human melanin-concentrating hormone (MCH) suitable for radioiodination was designed in which Tyr¹³ and Val¹⁹ of the natural peptide were replaced by phenylalanyl and tyrosyl residues: [Phe¹³, Tyr¹⁹] -MCH. The peptide was synthesized by the continuous-flow solid-phase methodology using Fmocstrategy and Polyhipe PA 500 and PEG-PS resins. The linear MCH peptides with either acetamidomethyl-protected or free cysteinyl residues were purified to homogeneity and cyclized by iodine oxidation, yielding the final product with the correct molecular weight of 2434.61. Radioiodination of the C-terminal tyrosine was carried out enzymatically using solid-phase bound glucose oxidase/lactoperoxidase, followed by purification on a reversed-phase mini-column and by high-pressure liquid chromatography. The resulting [¹²⁵I]-[Phe¹³, Tyr¹⁹]-MCH tracer was the first radiolabelled MCH peptide suitable for radioreceptor assay: saturation binding analysis using mouse G4F-7 melanoma cells demonstrated the presence of 1090 MCH receptors per cell. The dissociation constant (KD ) was 1.18 × 10^?10 M, indicating high-affinity MCH receptors on these cells. MCH receptors were also found in other cell lines such as mouse B16-F1 and G4F and human RE melanoma cells as well as in PC12 and COS-7 cells. Competition binding analyses with a number of other peptides such as α-MSH, neuropeptide Y, substance P and pituitary adenylate cyclase activating peptide, demonstrated that the binding to the MCH receptor is specific. Atrial natriuretic factor was found to be a weak competitor of MCH, indicating topological similarities between MCH and ANF when interacting with MCH receptors.     

Identification and characterization of a UDP-GalNAc:GlcNAc{eta}-R {eta}->4-N-acetylgalactosaminyltransferase from cercariae of the schistosome Trichobilharzia ocellata. Catalysis of a key step in the synthesis of N,N'-diacetyllactosediamino (lacdiNAc)-type glycans

Three different stages of the avian schistosome Trichobilharziaocellata appeared to contain a novel N-acetylgalac-tosaminyltransferaseactivity. To investigate its function in the biosynthesis ofschistosome glycoconjugates, the enzyme was partially purifiedfrom cercariae, a free-living stage of the parasite, by affinitychromatography on UDP-Sepharose. Acceptor specificity studiesshowed that the enzyme catalyses the transfer of N-acetylgalactosamine(GalNAc) from UDP-GalNAc to oligosaccharides, glyco-peptidesand glycoproteins carrying a terminally