Regulation of hapten-specific T-cell response. II. Functional analysis of helper T cells and cytotoxic T cells in animals suppressed by azobenzenearsonate (ABA)-specific suppressor T cells

The administration of azobenzenearsonate-modified syngeneic spleen cells (ABA-SC) intravenously induces a population of first order hapten-specific inducer suppressor T cells (Ts1), which downregulate various aspects of T-cell-mediated immune responses via a well defined suppressor-T-cell pathway. In this study, we investigated the effects of these suppressor cells on the generation of ABA-specific cytolytic T lymphocytes (CTL) and helper T cells (Th) in vivo. We found evidence for functional impairment of ABA-activated Th and ABA-specific CTL precursors (CTLp) in the suppressed animals by a number of different in vitro criteria. Functional analysis of ABA-specific CTLp and ABA-activated Th in suppressed animals revealed that ABA-specific Ts inhibit the generation of CTL by impairing the antigen-specific activation of Th, which may in turn, prevent the clonal expansion of antigen-specific CTLp. The significance of these findings in relationship to our understanding of the cellular interactions necessary for the generation of CTL and the mode of action and mechanisms of suppressor T cells is discussed.     

Genetic basis and mapping of the resistance to rice yellow mottle virus. I. QTLs identification and relationship between resistance and plant morphology

 Rice yellow mottle virus (RYMV) resistance QTLs were mapped in a doubled-haploid population of rice, ‘IR64/Azucena’. Disease impact on plant morphology and development, expression of symptoms and virus content were evaluated in field conditions. Virus content was also assessed in a growth chamber. RYMV resistance was found to be under a polygenic determinism, and 15 QTLs were detected on seven chromosomal fragments. For all of the resistance QTLs detected, the favourable allele was provided by the resistant parent ‘Azucena’. Three regions were determined using different resistance parameters and in two environments. On chromosome 12, a QTL of resistance that had already been detected in this population and another indica/japonica population was confirmed both in the field and under controlled conditions. Significant correlations were observed between resistance and tillering ability, as measured on control non-inoculated plants. In addition, the three genomic fragments involved in resistance were also involved in plant architecture and development. In particular, the semi-dwarfing gene sd-1, on chromosome 1, provided by the susceptible parent, ‘IR64’, mapped in a region where resistance QTLs were detected with most of the resistance parameters. In contrast, the QTL of resistance mapped on chromosome 12 was found to be independent of plant morphology. Received: 20 April 1998 / Accepted: 30 April 1998     

Growth and fruitbody formation ofGanoderma lucidum on media supplemented with vanadium, selenium and germanium

Responses of mycelia ofGanoderma lucidum to vanadium, selenium and germanium were examined over a wide range of concentrations (10–1, 120 μg/ml) in pure culture. Se and V were found to be highly toxic, but Ge was not toxic at the levels tested.Ganododerma lucidum cultivated on substrates of sawdust with V (30–80 μg/g) developed mature fruitbodies, but the bioaccumulation of V was quite low (2.5–7 μg/g in pileus, 12.5–21.5 μg/g in stipe and <1 μg/g in basidiospores). Se as Na₂SeO₄ labeled with⁷⁵Se was effectively taken up from substrates and accumulated in fruitbodies (mainly in pileus), then depleted by discharge of basidiospores. Ge as GeCl₄ labeled with⁷⁷Ge was easily uptaken and translocated into fruitbodies.     

Hydrolysis and resynthesis of sucrose and related sugars in the developing stem tissues of Eucalyptus regnans trees

Summary When cambial tissues are removed from tree stems of Eucalyptus regnans F. Muell. and incubated in vitro with [¹⁴C]glucose, [¹⁴C]galactose and [¹⁴C]fructose in the presence of sufficient PVP (polyvinylpyrrolidone) radioactive sucrose, members of the raffinose family and related sugars are synthesized. These results suggest that PVP inactivates substances which, in in vitro experiments, inhibit the action of enzymes which are essential to the resynthesis of nutrient sugars (sucrose, raffinose and stachyose). In living trees, such enzyme inhibition is less likely to occur.     

Early induction of functional SARS-CoV-2-specific T cells associates with rapid viral clearance and mild disease in COVID-19 patients

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Chiral lumazines: Preparation,properties, enantiomeric separation

Optically active lumazines (biolumazine, dictyolumazine, monalumazine, and neolumazine) are prepared from the corresponding pterins by enzymatic reaction, using pterin deaminase excreted by Dictyostelium discoideum. The fluorescence properties, circular dichroism spectra, and chromatographic behavior of these lumazines are studied. D - and L -enantiomers of biolumazine, dictyolumazine, and monalumazine are separated using a chiral flavoprotein column. This column also separates the enantiomeric pterins of the threo form: monapterin and dictyopterin. However, the column does not separate the enantiomeric pterins of the erythro form: neopterin and biopterin. By coupling a reverse-phase column to the flavoprotein column, the separation of pterins and lumazines in function of their hydrophobicity, as well as the separation of the diastereomers, is achieved. This coupled achiral/chiral high-performance liquid chromatography method enables determination of the stereoconfiguration of natural lumazines by comparison with optically pure compounds. A lumazine derivative, present in the extracellular medium of Dictyostelium discoideum, is identified as D -dictyolumazine, i.e., 6-(D -threo-1,2-dihydroxypropyl)-lumazine. © 1994 Wiley-Liss, Inc.     

Purification and properties of guanosine 5', 3'-polyphosphate synthetase from Bacillus brevis.

A ribosome-independent guanosine 5',3'-polyphosphate synthetase has been highly purified from Bacillus brevis (ATCC 8185). The enzyme has a molecular weight of 55,000, as measured by sucrose density gradient centrifugation. Like the ribosome-connected stringent factor of Escherichia coli, it catalyzes the synthesis of the guanosine 5', 3'-polyphosphates by a pyrophosphoryl transfer mechanism from adenosine triphosphate (ATP) to guanosine di- or triphosphates (GDP, GTP). It has an apparent Km of 0.14 mM for GDP and 0.77 mM for GTP, and is specific for the guanosine ribonucleotides as pyrophosphoryl acceptors. Several ATP analogues were tested for their ability to donate the pyrophosphoryl group. Mg2+ was required as a counter ion for the nucleotide substrate; however, an excess of Mg2+ was inhibitory. The property of the B. brevis enzyme is compared with the ribosome-linked enzyme of E. coli and an extracellular enzyme excreted by several types of Streptomyces reported upon recently.     

Human papillomavirus vaccination for adults aged 30 to 45 years in the United States: A cost-effectiveness analysis

BackgroundA nonavalent human papillomavirus (HPV) vaccine has been licensed for use in women and men up to age 45 years in the United States. The cost-effectiveness of HPV vaccination for women and men aged 30 to 45 years in the context of cervical cancer screening practice was evaluated to inform national guidelines.Methods and findingsWe utilized 2 independent HPV microsimulation models to evaluate the cost-effectiveness of extending the upper age limit of HPV vaccination in women (from age 26 years) and men (from age 21 years) up to age 30, 35, 40, or 45 years. The models were empirically calibrated to reflect the burden of HPV and related cancers in the US population and used standardized inputs regarding historical and future vaccination uptake, vaccine efficacy, cervical cancer screening, and costs. Disease outcomes included cervical, anal, oropharyngeal, vulvar, vaginal, and penile cancers, as well as genital warts. Both models projected higher costs and greater health benefits as the upper age limit of HPV vaccination increased. Strategies of vaccinating females and males up to ages 30, 35, and 40 years were found to be less cost-effective than vaccinating up to age 45 years, which had an incremental cost-effectiveness ratio (ICER) greater than a commonly accepted upper threshold of $200,000 per quality-adjusted life year (QALY) gained. When including all HPV-related outcomes, the ICER for vaccinating up to age 45 years ranged from $315,700 to $440,600 per QALY gained. Assumptions regarding cervical screening compliance, vaccine costs, and the natural history of noncervical HPV-related cancers had major impacts on the cost-effectiveness of the vaccination strategies. Key limitations of the study were related to uncertainties in the data used to inform the models, including the timing of vaccine impact on noncervical cancers and vaccine efficacy at older ages.ConclusionsOur results from 2 independent models suggest that HPV vaccination for adult women and men aged 30 to 45 years is unlikely to represent good value for money in the US.

Jane Kim and co-workers estimate the potential cost-effectiveness of papillomavirus vaccination for adults aged 30-45 years in the United States.