Suppression of lymphokine production: I. Macrophage-mediated inhibition of MIF production

Macrophages have been found to suppress the in vitro production by stimulated T lymphocytes of a lymphokine, migration inhibitory factor. When macrophages isolated from primary MSV-induced tumors were added to antigen-stimulated MSV-immune spleen cells, a complete suppression of MIF production was observed. This suppression was nonspecific, since MIF production by antigen-stimulated alloimmune spleen cells and by PHA-stimulated normal spleen cells was also inhibited. Suppressor macrophages could also be induced by inoculation with Corynebacterium parvum, whereas light mineral oil-induced peritoneal macrophages had no detectable effect on MIF production. The failure to detect MIF in the supernatants of stimulated cultures containing activated macrophages appeared to be due to inhibition of lymphokine production rather than to absorption or inactivation of MIF or to interference with the assay for detection of MIF. Macrophages were able to suppress MIF production only when added during the first 4–5 hr of culture and they had no effect when added later. These data show that activated macrophages can nonspecifically suppress lymphokine production and that this appears to be due to inhibition of an early step in lymphocyte stimulation.     

Protein phosphokinase activity of rat liver nuclear membrane

The presence of protein phosphokinase activity in a purified nuclear-membrane preparation from adult rat liver was demonstrated by measuring the incorporation of ³²P from γ-³²P-ATP into endogenous nuclear-membrane proteins as well as into the exogenous protein substrates, dephosphophosvitin (DPV) and lysine-rich histone (LRH). The activity of this enzyme toward DPV was 60 times greater than that toward LRH. cAMP and cGMP did not appear to affect the phosphorylation of endogenous-membrane proteins.     

Fluorescent thin-layer peptide mapping for protein identification and comparison in the subnanomole range

Conditions and simple precautions are presented for carrying out highly reproducible and sensitive peptide mapping by thin-layer chromatography and subsequent electrophoresis of subnanomole amounts of tryptic digest on silica gel G or GHL plates. The fluorogenic reagent “fluorescamine” is employed for visualization under long-wavelength ultraviolet illumination. Permanent photorecording of high-contrast images, using readily available filters, is substituted for subjective hand scoring of plates. Contrast reversal is used to produce peptide maps suitable for half-tone reproduction.     

Hyaluronidase activity and hyaluronate content of the developing chick embryo heart.

Hyaluronidase activity and hyaluronate content were measured in the developing chick heart from embryonic day 3 through posthatching stages. High levels of both enzyme and substrate were found during the earliest stages examined. Hyaluronidase activity gradually declined to 63% of the initial (day 3) level by embryonic day 16. Enzyme activity decreased more sharply during the next 4 days to 30% of the initial level and remained constant through 2 weeks after hatching. Low levels of enzyme activity (about 10% initial levels) were still detectable in 10-week-old chicken hearts. The heart hyaluronidase is an endoglycosidase with an estimated molecular weight of 62,000, which degrades hyaluronate and, to a lesser extent, chondroitin sulfate at an acid pH optimum. Hyaluronate constituted approximately 50% of the total glycosaminoglycan content at embryonic day 5. Between embryonic days 5 and 12, the concentration of hyaluronate decreased to 25–30% of the initial level and remained constant thereafter. The level of other glycosaminoglycans decreased more gradually than hyaluronate and did not reach a constant level until hatching. This pattern of hyaluronidase activity and hyaluronate concentration presumably reflects the extensive tissue remodeling which transforms the developing heart from a thin-walled tube containing extensive regions of extracellular matrix to a compact, thick-walled myocardium having a limited extracellular compartment.     

The influence upon mitogenic and cellular immunologic reactive systems in vitro by poly(I:C) and BCG murine interferons induced in vivo.

We have previously reported that lymphocytes from W/Fu rats immunized with syngeneic (C58NT)D tumor cells were cytotoxic against these cells in a 4-hr ⁵¹Cr release assay. We have investigated the feasibility of cryopreserving lymphocytes and target cells and have selected freezing conditions which provide good yields of viable cells and functional activity. Lymphocytes from different animals had a recovery of 60–80% viability which resulted in a corresponding 55–75% recovery of cytotoxic activity. Repeated testing of lymphocyte cytotoxicity from a pool of frozen spleen cells against either fresh or frozen (C58NT)D cells gave reproducible cytotoxicity. In addition, recovery of high levels of lymphocyte function was also demonstrated when cryopreserved cells were employed in long-term cytotoxic assays, i.e., ³H-proline and ¹²⁵IUdR release assays, in the lymphoproliferative response to mitogens (PHA and Con A)³ or tumor cells (MLTI) as measured by ³H-thymidine incorporation, and in the in vitro generation of secondary cytotoxicity.By employing these cryoprotective techniques it is possible to have: 1) a population of lymphoid cells with known functional activity and 2) a pool of target cells with known susceptibility to lysis and antigenic content. Furthermore, the use of frozen cells as internal standards in each test also permits the analysis of assay variation as well as the study of variation in various cell types.     

The subunit fine structure of isolated, purified Na,K-adenosine triphosphatase : Freeze-fracture study

The ultrastructural features of a purified fraction of Na⁺,K⁺-adenosine triphosphatase (ATPase) isolated from dog kidney medulla were compared with those of the initial crude microsomal fraction in the purification sequence. Although both fractions consist of vesicular structures, the purified fraction is more homogeneous with respect to overall size and intramembrane protein particle size and distribution. Polyacrylamide gel electrophoresis profiles of both fractions reveal multiple proteins in the microsomal fraction but only two in the final purified fraction. The membranes of the pure fraction comprised one class of particles roughly 95–120 Å in diameter which represent the in vitro configuration of Na⁺,K⁺-ATPase.     

Guidelines for model adaptation: A study of the transferability of a general seagrass ecosystem Dynamic Bayesian Networks model

In general, it is not feasible to collect enough empirical data to capture the entire range of processes that define a complex system, either intrinsically or when viewing the system from a different geographical or temporal perspective. In this context, an alternative approach is to consider model transferability, which is the act of translating a model built for one environment to another less well‐known situation. Model transferability and adaptability may be extremely beneficial—approaches that aid in the reuse and adaption of models, particularly for sites with limited data, would benefit from widespread model uptake. Besides the reduced effort required to develop a model, data collection can be simplified when transferring a model to a different application context. The research presented in this paper focused on a case study to identify and implement guidelines for model adaptation. Our study adapted a general Dynamic Bayesian Networks (DBN) of a seagrass ecosystem to a new location where nodes were similar, but the conditional probability tables varied. We focused on two species of seagrass (Zostera noltei and Zostera marina) located in Arcachon Bay, France. Expert knowledge was used to complement peer‐reviewed literature to identify which components needed adjustment including parameterization and quantification of the model and desired outcomes. We adopted both linguistic labels and scenario‐based elicitation to elicit from experts the conditional probabilities used to quantify the DBN. Following the proposed guidelines, the model structure of the general DBN was retained, but the conditional probability tables were adapted for nodes that characterized the growth dynamics in Zostera spp. population located in Arcachon Bay, as well as the seasonal variation on their reproduction. Particular attention was paid to the light variable as it is a crucial driver of growth and physiology for seagrasses. Our guidelines provide a way to adapt a general DBN to specific ecosystems to maximize model reuse and minimize re‐development effort. Especially important from a transferability perspective are guidelines for ecosystems with limited data, and how simulation and prior predictive approaches can be used in these contexts.     

不同颜色遮阳网遮光对丘陵茶园夏秋茶和春茶产量及主要生化成分的影响

为研究不同颜色遮阳网遮光对夏秋茶与春茶产量和品质的影响,在中国科学院桃源农业生态试验站以“碧香早”茶树为试验材料,选用不遮光和中度遮光（遮光率(50?4)%）的黑色、绿色、银灰色遮阳网开展遮光试验。结果表明：不同季节使用黑色遮阳网能显著增加氨基酸和咖啡碱含量,降低茶多酚含量和酚氨比,与对照茶园比较,夏季、秋季、春季茶叶氨基酸含量分别增加了14.22%、17.07%、6.23%,茶多酚含量分别降低了4.40%、6.43%、27.66%,咖啡碱含量分别增加了9.48%、8.10%、7.28%。夏秋季银灰色遮阳网效果最差,绿色遮阳网效果介于黑色和对照之间,春季三种颜色遮阳网效果均优于对照;茶树遮光后品质明显优于对照,夏秋茶经遮光可达到制高档茶的要求,春茶遮光可达到制名优茶的要求。     

Long COVID and its Management

The pandemic of COVID-19 is the biggest public health crisis in 21^st Century. Besides the acute symptoms after infection, patients and society are also being challenged by the long-term health complications associated with COVID-19, commonly known as long COVID. While health professionals work hard to find proper treatments, large amount of knowledge has been accumulated in recent years. In order to deal with long COVID efficiently, it is important for people to keep up with current progresses and take proactive actions on long COVID. For this purpose, this review will first introduce the general background of long COVID, and then discuss its risk factors, diagnostic indicators and management strategies. This review will serve as a useful resource for people to understand and prepare for long COVID that will be with us in the foreseeable future.     

不同农业土地利用方式和管理对土壤有机碳的影响 ——以北京市延庆盆地为例

自20世纪80年代以来,我国农业土地利用方式和农田管理发生了巨大变化,由此引起的土壤有机碳（SOC）含量、密度及其垂直分布发生了相应的变化,研究不同土地利用方式和管理对土壤有机碳的影响对于探讨农田生态系统的固碳作用具有重要的意义.以北京市延怀盆地为典型研究地区,选择6种农业土地利用和管理模式,共计42块样地,在1m深土体内分层采集197个土壤样品.研究结果表明：（1） 不同农业土地利用和管理方式对SOC含量的影响主要发生在0～25 cm土层中,剖面中SOC含量自上向下明显降低.（2） 通过对6种土地利用和管理方式下土壤SOC含量进行比较,结果发现果园和高投入的玉米地土壤在0～100 cm土层中SOC含量均较高,变化范围分别为4.16～10.00 g kg^-1和4.73～9.31 g kg^-1; 菜地土壤在0～40 cm土层中SOC含量较高,变化范围为6.42～9.67 g kg^-1;大豆地、中、低投入玉米地土壤在0～100 cm土层中SOC含量较低,变化范围分别为3.27～7.73 g kg^-1、3.14～8.33 g kg^-1和1.83～7.67 g kg^-1. （3） 不同农业土地利用方式对SOC密度影响的趋势与对SOC含量影响的趋势基本一致,在0～100 cm土壤中,SOC密度的顺序为果园＞菜地＞高投入玉米地＞中投入玉米地＞大豆地＞低投入玉米地,变化范围为4.15～8.22 kg m^-2.