Solid-Phase Synthesis of Biaryl Cyclic Peptides Containing a Histidine-Phenylalanine Linkage

The feasibility of the solid-phase intramolecular 4(5)-arylation of a histidine residue to obtain biaryl cyclic peptides bearing a His-Phe linkage was esta     

Plasma Biomarkers Discriminate Clinical Forms of Multiple Sclerosis

Multiple sclerosis, the most common cause of neurological disability in young population after trauma, represents a significant public health burden. Current challenges associated with management of multiple sclerosis (MS) patients stem from the lack of biomarkers that might enable stratification of the different clinical forms of MS and thus prompt treatment for those patients with progressive MS, for whom there is currently no therapy available. In the present work we analyzed a set of thirty different plasma cytokines, chemokines and growth factors present in circulation of 129 MS patients with different clinical forms (relapsing remitting, secondary progressive and primary progressive MS) and 53 healthy controls, across two independent cohorts. The set of plasma analytes was quantified with Luminex xMAP technology and their predictive power regarding clinical outcome was evaluated both individually using ROC curves and in combination using logistic regression analysis. Our results from two independent cohorts of MS patients demonstrate that the divergent clinical and histology-based MS forms are associated with distinct profiles of circulating plasma protein biomarkers, with distinct signatures being composed of chemokines and growth/angiogenic factors. With this work, we propose that an evaluation of a set of 4 circulating biomarkers (HGF, Eotaxin/CCL11, EGF and MIP-1β/CCL4) in MS patients might serve as an effective tool in the diagnosis and more personalized therapeutic targeting of MS patients.     

Regulation of sulphur amino acids metabolic enzymes in Cephalosporium acremonium strains differing in antibiotic production

Three strains of Cephalosporium acremonium with different potential of cephalosporin C production show differences in the levels of sulphur amino acid metabolic enzymes. The regulation of these enzymes is also different in the strains. In the superior producing strain two enzymes directly involved in cysteine synthesis are the least susceptible to repression by methionine. In this strain cystathionine metabolizing enzymes seem to favour cysteine synthesis. Antibiotic producing strains, in contrast to the non-producing strain, are highly sensitive to chromate.     

Multiple and alternative adhesive responses on defined substrata of an immortalized dorsal root neuron hybrid cell line

Attachment and neurite extension processes have been evaluated for an immortalized derivative cell of a rat dorsal root neuron after fusion with a mouse neuroblastoma cell (the clonal F11 hybrid cell line) and these processes compared with previous studies of neuroblastoma cells, since both cell types may be derived from the neural crest of the developing embryo. Biochemically defined substrata were provided by human plasma fibronectin (pFN), the heparan sulfate-binding protein platelet factor-4 (PF4), and the ganglioside GM1-binding protein cholera toxin B subunit (CTB). While some attachment of unsupplemented cells was noted on CTB substrata, GM1 supplementation permitted F11 cells to attach as well on CTB as on pFN or PF4. On PF4, very few neurite processes were observed while on pFN two morphologically distinct types of neurites could be identified: short, linear processes in a low percentage of cells resembling those of neuroblastoma cells and long, irregular and narrow processes in a higher percentage of cells resembling those of dorsal root neurons. On CTB, neurites of the latter class were even more prominent; however, cell bodies on CTB failed to spread by cytoplasmic extension as commonly observed in F11 cells on pFN and, to some extent, on PF4. The formation of both neurite classes on either pFN or CTB was completely inhibited by low concentrations of an RGDS (Arg-Gly-Asp-Ser) peptide in the medium of cultures, indicating the significance of pFN's binding to cell surface integrin or ganglioside GM1's possible interaction with integrin for mediating the differentiative process. In contrast, neurite formation of neuroblastoma cells is refractile to the soluble peptide as reported previously. Neurite extensions of F11 cells on either pFN or CTB were comparably sensitive to low concentrations of cytochalasin D, revealing the mediation of microfilament reorganization in these processes. Treatment of F11 cells with cycloheximide failed to inhibit neurite extension on pFN but did partially inhibit extension on CTB; this contrasts with the very high sensitivity of neurite formation by neuroblastoma cells on CTB substrata reported previously.(ABSTRACT TRUNCATED AT 400 WORDS)     

Successional pathways of Mediterranean evergreen vegetation on Sicily

The Mediterranean evergreen vegetation of Sicily, comprised in the belt of the Quercetea ilicis, occupies a large part of the island. Human intervention (cutting, fire, pasture) has brought about a degradation of the natural vegetation. This study is based on our phytosociological research of the Quercetea ilicis belt on Sicily.

With the ‘habitat comparison’ method, the dynamical relations between the different vegetation units have been defined.

We distinguish the following stages, with reference to their vegetation structure:

• a herbaceous stage formed by steppic vegetation, preceded by various types of nitrophilous-ruderal vegetation on abandoned fields;

• a garrigue stage dominated by half-shrubs;

• a macquis stage with various distinct plant communities, four communities being important in regressive successions, and three in progressive ones;

• a woodland and shrub-woodland stage with three different substages: pre-existent forests, present woodlands, and woodlands which tend towards the final, stable stage of vegetation (potential natural vegetation).

The dynamic relationships both in progressive and regressive successions have been synthesized in a scheme. In this scheme we have shown the main stages of the vegetation in their dynamics and we have constructed different series of vegetation types in two altitudinal belts, which are determined by varying environmental conditions of today.

The results also show that in some cases the progressive series follow different pathways than the regressive series, and the final stage of the progressive series is different from the original vegetation.

     

Direct visualization of the sites of DNA methylation in human,and mosquito chromosomes

Human and mosquito fixed chromosomes were digested with restriction endonucleases that are inhibited by the presence of 5-methylcytosine in their restriction sites (Hha I, Hin PI, Hpa II), and with endonucleases for which cleavage is less dependent on the state of methylation (Taq I, Msp I). Methylation-dependent enzymes extracted low DNA amounts from human chromosomes, while methylation-independent enzymes extracted moderate to high amounts of DNA. After DNA demethylation with 5-azacytidine the isoschizomers Hpa II (methylation-dependent) and Msp I (methylation-independent) extracted 12-fold and 1.4-fold amounts of DNA from human chromosomes, respectively. These findings indicate that human DNA has a high concentration of Hpa II and Msp I restriction sites (CCGG), and that the internal C of this sequence is methylated in most cases, while the external cytosine is methylated less often. All the enzymes tested released moderate amounts of DNA from mosquito chromosomes whether or not the DNA was demethylated with 5-azacytidine. Hpa II induced banding in the centromere chromosome regions. After demethylation with 5-azacytidine this banding disappeared. Mosquito DNA has therefore, moderate to high frequencies of nonmethylated CpG duplets. The only exception is the centromeric DNA, in which the high levels of C methylation present produce cleavage by Hpa II and the appearance of banding. Centromere regions of human chromosomes 1 have a moderately low concentration of Hpa II-Msp I restriction sites.     

Use of tritium labeled amino acid conjugates of prostaglandins and thromboxanes as labeled ligands in prostanoid radioimmunoassay

Conjugates of prostaglandins and thromboxanes with tritium labeled amino acids were prepared and employed as labeled ligands in porstaglandin and thromboxane radioimmunoassays. Assays for PGF_2α, 15-keto-13, 14-dihydro-PGF_2α, TXB₂ and 15-keto-13, 14-dihydro-TXB₂ were evaluated in comparative studies using either these heterologous ligands or the corresponding homologus tritiated eicosanoid as tracers. Binding properties for the respective antibodies were found to be similar using either tracer.Three biological studies were also conducted, viz. study of the release of TXB₂ during collagen induced platelet aggregation, of 15-keto-13, 14-dihydro-TXB₂ during guinea pig pulmonary anaphylaxis, and of PGF_2α (measured as 15-keto-13, 14-dihydro-PGF_2α in peripheral plasma) during bovine luteolysis. The analyses gave comparable results using either the heterologous or the homologous assay.Thus, this type of labeled prostanoid conjugates may serve as a convenient alternative to homologous tracers in radioimmunoassay. Heterologous tracers may even in certain cases provide the only simple solution to the problem of preparing a labeled ligand of high specific activity.     

Tubular structures associated with the endothelial endoplasmic reticulum in glomerular capillaries of Rhesus monkey and nephritic man

Summary Round bodies, tubular profiles and crystalline images have been studied by electron microscopy in the endothelium of seven normal young Rhesus monkeys and in the renal glomerular endothelium of two nephritic human patients. The crystalline images are most frequently formed by aggregation of round bodies, 200–240 Å in diameter. In Rhesus monkeys a variety of crystalline images are seen. On the contrary, in nephritic patients round bodies and tubular profiles are rare and less organized. In the glomerular endothelium of two normal men they were not found.The results obtained suggest that the round bodies, the tubular profiles and the crystalline images result from sectioning of a system of undulating tubules associated with the smooth endoplasmic reticulum. In nephritic patients the formation of such a tubular system could represent a change taking place within the affected cells as a pathologic response to the disease.This work was supported by U.S. Public Health Service (N.H.I.), Grant AI-04527-03-04, and by the Consiglio Nazionale delle Ricerche (C.N.R.), Contributo 115/0815/0-1365. The Authors are greatly indebted to Miss Hermina Spiele for skilful technical assistance.     

Four new species of yeast isolated from insect frass in bark ofTsuga heterophylla (Raf.) Sargent

Summary In a study of the yeasts associated with insect frass underneath the bark ofTsuga heterophylla (the Pacific Coast hemlock) four new species of yeast were found. These were described asSporobolomyces singularis, Bullera tsugae, Cryptococcus skinneri andCandida oregonensis. Sporobolomyces singularis is a non-pigmented species, which required an amendment of the genus definition. Ballistospore formation of the new species ofSporobolomyces and ofBullera was absent on malt agar and on potato glucose agar, but positive on corn meal agar. An unusual case of quantitative transgalactosylation by growing cells ofSporobolomyces singularis on lactose has been described. It has been proposed to establish a “Candida parapsilosis Group” of species to whichC. oregonensis was assigned. Supported by a fellowship of the Calouste Gulbenkian Foundation, Lisbon, Portugal.     

Antimicrobial activity of clove oil dispersed in a concentrated sugar solution

Essential oil of clove, dispersed (0.4%v/v) in a concentrated sugar solution, had a marked germicidal effect against various bacteria and Candida albicans. Staphyloccus aureus (five strains), Klebsiella pneumoniae, Pseudomonas aeruginosa, Clostridium perfringens , and Escherichia coli inoculated at a level of 10⁷ cfu/ml, and C. albicans (inoculum 4.0×10⁵ cfu/ml) were killed (< 99.999%) after 2–7 min in a laboratory broth supplemented with 63% (v/w) of sugar, and containing 0.4% (v/w) of essential oil of clove. Added organic matter (i.e. human or bovine serum) did not impair its antimicrobial activity.
Sugar was not necessary for the antimicrobial activity of clove oil, but the concentrated sugar solution provided a good vehicle for obtaining an oil dispersion that is relatively stable for certain practical applications.