How B cells and dendritic cells may cooperate in antigen purification

The specificity of the immunological responses is achieved through the cooperation of three classes of cells: B and T lymphocytes, and dendritic cells (DCs). A critical, intensely studied interaction is that between DCs and T cells, during which the DC presents MHC-bound antigenic fragments to the T cell receptor (TCR). There has been recent excitement about the possibility of increasing the signal-to-noise ratio in the detection of cognate antigen-TCR couples, by the use of kinetic proofreading mechanisms. We examine here the signal-to-noise problem in a broader perspective, and in particular, address the question of possible "antigen purification" mechanisms, prior to their presentation to the T cells. Ways in which the DCs might concentrate, purify and preserve their load of captured antigens are considered: (i) If antigens can be transferred from one DC to another, in such a way that the richer a DC in antigen, the more it captures antigens from other DCs, the antigens may end up concentrated in a small subset of DCs, (ii) antigen purification may be achieved through recycling interactions between DCs and B cells. A DC would transmit to a B cell antigen mixtures, and the DC would recapture only the antigens which can bind to the B cell's antibodies and (iii) dendrites, when they are present, may play an essential role in recapturing the antigens that were used in interactions of DCs with T cells, B cells, or other DCs, thereby reducing antigen losses. More generally, we provide a personal interpretation of cell-to-cell antigen transfers, in terms of a strategy in which there is a progressive emergence, through multiple interactions, of subsets of cells of each type better and better prepared for the subsequent rounds of interactions.     

Nonparametric and semiparametric trend analysis for stratified recurrence times

Recurrent event data are frequently encountered in longitudinal follow-up studies when the occurrences of multiple events are considered as the major outcomes. Suppose that the recurrent events are of the same type and the variable of interest is the recurrence time between successive events. In many applications, the distributional pattern of recurrence times can be used as an index for the progression of a disease. Such a distributional pattern is important for understanding the natural history of a disease or for confirming long-term treatment effect. In this article, we discuss and define the comparability of recurrence times. Nonparametric and semiparametric methods are developed for testing trend of recurrence time distributions and estimating trend parameters in regression models. The construction of the methods is based on comparable recurrence times from stratified data. A real data example is presented to illustrate the use of methodology.     

Effect of variation in photoperiodic response on diapause induction and developmental time in the willow leaf beetle, Plagiodera versicolora

The willow leaf beetle, Plagiodera versicolora (Coleoptera: Chrysomelidae) overwinters in adult diapause. In this study, the photoperiodic responses for diapause induction and developmental time were examined in the Ishikari (Hokkaido, Japan) population of P. versicolora. All females entered reproductive diapause under short daylength (L10:D14), but 31.7% of females did not enter diapause under long daylength (L16:D8). The developmental time from oviposition to adult emergence was significantly longer at L10:D14 than that at L16:D8. Norm of reaction curves illustrated variation among families in the photoperiodic responses for diapause induction and for developmental time. ANOVA indicated significant family × photoperiod interactions in the developmental time. At L16:D8, developmental time was positively correlated with the incidence of diapause in females. This means that a female having a longer developmental time tends to have a longer critical photoperiod. Such variation may be maintained by differences in selection pressures on the growth rate and the critical photoperiod for diapause induction between univoltine and bivoltine genotypes because Ishikari is located in a transitional area between populations with univoltine and bivoltine life cycles.     

Somatic embryogenesis in the endemic black iris

Apple shoot cultures accumulate phenolic acids, flavonols, catechins, and procyanidins. Increasing the sucrose content and reducing the macronutrient content of culture media both resulted in an enhanced content of phenolic substances. The qualitative composition of the substances was affected as well. Morphology of the shoots, preculture and time of sampling in the subculture interval influenced the reaction pattern.     

The supercritical birth,death and catastrophe process: Limit theorems on the set of non-extinction

The skip-free property of the super-critical linear birth and death process with a linear catastrophe component is exploited to obtain an almost sure convergence theorem for the population size without any extra moment assumptions. This completes some earlier work of the author. A proof is sketched of a central limit theorem for the logarithm of the population size. Identification of the form of the norming constants for this result requires estimates of the extinction probabilities as functions of the initial population size. This is related to moment conditions on the decrement distribution.Most of this research was carried out at Colorado State University with the partial support of N.S.F. grant DMS-8501763.     

不同时机行血管介入栓塞术治疗颅内动脉瘤的疗效及对患者预后、神经功能和血清炎性因子的影响

摘要 目的：探讨不同时机行血管介入栓塞术治疗颅内动脉瘤的疗效及对患者预后、神经功能和血清炎性因子的影响。方法：选择2019年3月到2020年12月期间我院收治的80例颅内动脉瘤患者,按手术时间的不同将其分为早期组、延期组,其中早期组36例,发病至手术时间≤72 h;延期组44例,发病至手术时间＞72 h,对比两组疗效、预后、神经功能、血清炎性因子及并发症发生率。结果：早期组的完全栓塞率高于延期组,基本栓塞率低于延期组（P<0.05）。两组术后3个月美国国立卫生研究院卒中量表（NIHSS）、改良Rankin量表评分均较术前下降,且早期组低于延期组（P<0.05）。早期组的预后良好率高于延期组（P<0.05）。两组术后3 d血清白介素-6（IL-6）、肿瘤坏死因子-α（TNF-α）水平下降,且早期组低于延期组（P<0.05）,白介素-10（IL-10）水平升高,且早期组高于延期组（P<0.05）。早期组的并发症发生率低于延期组（P<0.05）。结论：早期行血管介入栓塞术治疗颅内动脉瘤患者,可提高完全栓塞率,减轻神经功能损伤及炎性应激,降低并发症的发生风险,促进预后和生活质量改善。     

Metabolic engineering in strawberry fruit uncovers a dormant biosynthetic pathway

Wild strawberry (Fragaria vesca) fruit contains several important phenylpropene aroma compounds such as eugenol, but cultivated varieties are mostly devoid of them. We have redirected the carbon flux in cultivated strawberry (Fragaria×ananassa) fruit from anthocyanin pigment biosynthesis to the production of acetates of hydroxycinnamyl alcohols, which serve as the precursors of the phenylpropenes, by downregulating the strawberry chalcone synthase (CHS) via RNAi-mediated gene silencing and, alternatively, by an antisense CHS construct. Simultaneous heterologous overexpression of a eugenol (EGS) and isoeugenol synthase (IGS) gene in the same cultivated strawberry fruits boosted the formation of eugenol, isoeugenol, and the related phenylpropenes chavicol and anol to concentrations orders of magnitude greater than their odor thresholds. The results show that Fragaria×ananassa still bears a phenylpropene biosynthetic pathway but the carbon flux is primarily directed to the formation of pigments. Thus, partial restoration of wild strawberry flavor in cultivated varieties is feasible by diverting the flavonoid pathway to phenylpropene synthesis through metabolic engineering.