Sterols from three Lactarius species

The sterol composition of three fungi was determined. Ergosterol is the major sterol, accompanied by other closely related sterols.     

Neutral amino acids in the brain: changes in response to food ingestion

Abstract— The brain levels of each of the aromatic and branched-chain amino acids change 2 h after fasting rats begin to consume either a carbohydrate-fat diet or a similar diet containing 18% or 40% protein. Carbohydrate-fat ingestion elevates the concentrations of each of the aromatic amino acids in brain, while substantially depressing those of the branched-chain amino acids. The inclusion of protein in this diet suppresses the increases in brain aromatic amino acids and attenuates the decreases in the branched-chain amino acids. The changes in the brain level of each neutral amino acid following the ingestion of any of these diets correlate extremely well with the effects of the diet on the serum neutral amino acid pattern, specifically on the serum concentration ratio of each neutral amino acid to the sum of the other neutral amino acids. The diet-induced changes in the brain level of each of the amino acids also correlate surprisingly well with the calculated rate of brain influx for each amino acid.     

T1 oligonucleotides that segregate with tropism and with properties of gp70 in recombinants between N- and B-tropic murine leukemia viruses.

We have analyzed large RNase T1-resistant oligonucleotides derived from the genomes of 16 recombinants between N- and B-tropic murine leukemia viruses of BALB/c. The parental viruses, designated SP-N and LP-B, differ in several phenotypic or biochemically defined properties: N- or B-tropism; XC plaque morphology, electrophoretic mobility of three virion proteins (p15, p30, and gp70); ability to induce GIX antigen on infected cells; presence of 6 to 8 (out of 36 to 38 analyzable) large T1 oligonucleotides. One SP-N-specific T1 oligonucleotide was inherited by all 16 N-tropic recombinants and, thus, appears to be linked to N-tropism. This oligonucleotide lies in the 5' third of the oligonucleotide map of SP-N. One LP-B-specific T1 oligonucleotide was inherited by all 11 recombinants whose gp70 has an electrophoretic mobility like that of LP-B gp70 and that, like LP-B, fail to induce GIX antigen. This oligonucleotide lies in the 3' third of the oligonucleotide map of LP-B.     

Inhibition of human seminal fluid and Leishmania donovani phosphatases by molybdate heteropolyanions

Inhibition of a tartrate-resistant acid phosphatase (ACP) from Leishmania donovani and the tartrate-sensitive ACP from human seminal fluid (prostatic ACP) was examined using a series of 13 molybdate-containing heteropolyanions. The heteropolyanions were divided into four groups based on the number of molybdenum atoms they contain: Group I, Mo4; Group II, Mo6-8; Group III, Mo12; Group IV, Mo18. Two of the four groups, those consisting of compounds that contain either an Mo4 unit or an Mo18 unit with a heteroatom in the central cavity, were potent inhibitors and exhibited the highest degree of selectivity against the leishmanial and seminal fluid ACPs. The inhibition of prostatic ACP by complex E2 could be completely reversed by dialysis. Little inhibition of the acid phosphatase, beta-glucuronidase, or alpha-mannosidase from human spleen was observed with complexes B' and E2. For the seminal fluid phosphatase, the Ki values obtained with arsenate and vanadate depended markedly on pH, suggesting that, unlike most other phosphatases, the conformation of the inhibitor binding site on human seminal fluid ACP is pH-dependent. Results of competition experiments performed with various inhibitor pairs indicated that complex D2 binds to the active site of prostatic ACP while complex M binds at some site on the enzyme that affects the active site. Binding of complex M also modifies the affinity of the enzyme for other inhibitors such as vanadate. The potency of several heteropolyanion complexes and their selective inhibition of pathophysiologically significant acid phosphatases indicate that these compounds may have value as tools for study of the structure and function of this class of enzyme and perhaps in the therapy of human disease.     

Factors affecting chloride conductance in apical membrane vesicles from human placenta

Summary Apical membrane vesicles from human term placenta were isolated using a magnesium precipitation technique, and the purity of the vesicles was assessed morphologically using scanning and transmission electron microscopy, and biochemically, using marker enzymes. The vesicles were found to be morphologically intact and significantly enriched in enzymes associated with apical membranes. ³⁶Cl^– uptake into these vesicles was studied in the presence of an outwardly directed Cl^– gradient. This uptake was found to be time dependent, with an initial rapid uptake tending to peak between 10 and 20 min and thereafter decline. Uptake was found to be voltage dependent since 5 m valinomycin caused a decrease in uptake. The effects of N-phenylanthranilic acid (NPA) and 4,4-diisothiocyanostilbene-2,2-disulphonic acid (DIDS) and bumetanide on the initial rate of Cl^– were examined in the presence and absence of 5 m valinomycin. NPA and DIDS inhibited isotope uptake strongly with IC₅₀ values of 0.83±0.35 m and 3.43±0.37 m, respectively, in the absence of valinomycin. Although valinomycin reduced ³⁶Cl^– uptake by about 80% when added before the isotope, DIDS reduced the uptake which remained in a concentration-dependent fashion with an IC₅₀ of 5.6±2.1 m. Under these conditions, NPA was without effect at concentrations below 100 m. Bumetanide was without effect at the concentrations used in the absence of valinomycin. However, following valinomycin pretreatment, bumetanide reduced ³⁶Cl^– uptake significantly at 100 m concentration. Vesicle diameter, as assessed by flow cytometry, did not change under the conditions employed.The effects of some fatty acids were also investigated. Arachidonic acid and linoleic acid inhibited Cl^– uptake with IC₅₀ values of 37.6±14.9 m and 4.59±0.51 m, respectively. Arachidonyl alcohol and elaidic acid were found to be without effect. These studies show that human placental brush border membrane vesicles possess a chloride conductance channel, the activity of which can be measured in the presence of an outwardly directed Cl^– gradient and this channel is sensitive to Cl^– channel inhibitors, especially N-phenylanthranilic acid, and can be inhibited by unsaturated fatty acids such as arachidonic acid and linoleic acid.This work was supported in part by the Cystic Fibrosis Association of Ireland and Eolas, The Irish Science and Technology Agency. The technical assistance of Mr. Cormac O' Connell in the preparation of the electron micrographs and of Mr. Roddy Monks in the flow cytometric analysis is gratefully acknowledged.     

Psychophysical studies of the itch sensation and itchy skin ("alloknesis") produced by intracutaneous injection of histamine.

Psychophysical measurements of itch and itchy skin ("alloknesis"--itch produced by innocuous mechanical stimulation) were obtained in human volunteers following intracutaneous or subcutaneous injections of histamine or papain into the volar forearm. Histamine and papain were given in doses of 0.1, 1, or 10 micrograms in 10 microliters of saline. The effects of the depth of injection and of skin temperature on the latency, magnitude, and duration of itch were examined. Also, dose-response functions were obtained for the area of alloknesis produced by intracutaneous injections of histamine. Finally, the neural mechanisms underlying the spread of alloknesis were investigated via local anesthesia of the skin. Intracutaneous and subcutaneous injections of histamine, but not papain, produced a sensation of itch without pain. The latency of itch was shorter after an intracutanous than after a subcutaneous injection of histamine. The mean latencies of itch produced by a 1-microgram dose were 9.5 and 23.0 sec for intracutaneous and subcutaneous injections, respectively. No differences were observed in the magnitude or duration of itch. Similarly, the latency of itch was increased when the skin temperature at injection site was lowered to 15 degrees C, whereas the magnitude and duration of itch were unaffected. Intracutaneous and subcutaneous injections of histamine produced similar areas of alloknesis. However, the magnitude and duration of alloknesis were dependent on dose. The mean maximum areas of alloknesis produced by intracutaneous injections of 0.1, 1, and 10 micrograms of histamine were 28.3, 47.2, and 43.8 cm2, respectively. Alloknesis was present at 2 min after injection, increased to a maximum area without 10 min, and then gradually decreased during the next 25-40 min.(ABSTRACT TRUNCATED AT 250 WORDS)     

Point mutations at the thymidine kinase locus in L5178Y mouse lymphoma cells II. Test validation and interpretation

The L5178Y Mouse Lymphoma TK assay was studied extensively to determine if this mammalian cell assay for gene mutations at the thymidine kinase (TK) locus could provide valid, interpretable determinations of mutagenic potential, and whether this information is of value in the safety evaluation of chemicals. We first determined that test-derived TFT^R mutants were phenotypically stable, possessing little or no thymidine kinase activity as measured by labeled thymidine uptake, but demonstrating 100% cross resistance to bromodeoxyuridine. Common solvent vehicles such as acetone, dimethylsulfoxide and ethanol were shown to produce little cytotoxicity and no mutagenic activity when present at 1% levels. Out of a total of 10 noncarcinogens tested, all were negative when results were analyzed by a 2-sample log_et test on control and treated mutant count means. Of the 13 putative animal carcinogens tested, 10 were positive, 2 were negative (auramine O and sodium phenobarbital), and 1 showed sporadic activity (hydrazine sulfate) in the TK assay on the basis of test-derived t statistics. 2 compounds, 1,2-epoxybutane and ICR 191, which have been described as Ames positive non-carcinogens, were also positive in the TK assay. Although this sampling of a total of 29 compounds is insufficient for precise estimations of expected false-positive or false-negative frequencies, these data indicate the TK assay can be expected to detect a majority of carcinogens as mutagens including some missed by more established point-mutation assays.     

Révision systématiquedu genre Steginoporella smitt, 1873 (Bryozoa Cheilostomata)

Systematic revision of the genus Steginoporella: until now about eighty species were described. Only twenty recent species and thirty-four fossil ones are maintained. Several species and subspecies are new.The main interest of this revision is to establish a biostratigraphical scale: the settlement of this scale is based on the known stratigraphical distribution and on an attempt of phylogeny.The second advantage is ecological: all recent species live in marine tropical environment. The Steginoporella are good paleoecological indicators.At last, the establishment of a paleobiogeography, even incomplete and not definitive, allows to understand more easily recent distribution of Steginoporella connected with the great events of earth evolution.     

The chemical nature of osmium tetroxide fixation and staining of membranes by x-ray photoelectron spectroscopy.

X-ray photoelectron spectroscopy was used to determine the oxidation states of osmium compounds present in erythrocyte ghost preparations and related systems treated with osmium tetroxide. Osmium tetroxide and cholesterol, codeposited at -100 degrees C, began to react at -70 degrees C, and Os(VI) was formed. Similarly, Os(VI) was detected for the known cholesterol-osmate ester prepared and purified chemically. However, osmium tetroxide applied in phosphate buffer (pH 7.2) gave rise to large proportions of Os(IV) and Os(III) species in addition to Os(VI) compounds. Egg phosphatidylcholine likewise produced a mixture of Os(VI), Os(IV), and Os(III), but dipalmitoyl phosphatidylcholine failed to give significant amounts of osmium containing products under identical conditions. Glutaraldehyde gave a mixture of compounds with the same osmium oxidation states when allowed to react with aqueous osmium tetroxide. Unfixed and glutaraldehyde-fixed erythrocyte ghosts also produced mixtures of Ss(VI), Os(IV) and Os(III) under conditions identical to those of normal tissue processing. Additionally, the mixture of adducts initially formed by treatment with osmium tetroxide was further reduced by dehydration of the tissue with ethanol, rpesulting in a final mixture which was 50-60% Os(III). The results support a scheme for the reaction os osmium tetroxide with tissues in which the initial reaction site is the double bonds of unsaturated lipids to form Os(VI) derivatives. Subsequent hydrolysis and further reduction yield complexes of Os(IV) and Os(III). A mixture of these three states is present in membrane specimens during microscopic observation. Os(VI) and Os(IV) could be present as osmate esters and osmium dioxide, respectively; Os(III) could be present as an oxo- or amino complex(es). The photoelectron spectrum of intact erythrocyte ghosts can be synthesized from the spectra of phospholipid and cholesterol only, suggesting the predominance of the reaction with lipids in the fixation process.