Inhibition of lectin stimulation of murine lymphocytes by mescaline

Evidence is presented that the T-cell specific stimulation of mouse lymphocytes by concanavalin A is inhibitable by mescaline. The degree of lectin inhibition is directly proportional to the amount of mescaline added to the in vitro cell incubation. Results also suggest that, during in vitro incubation, mescaline becomes covalently conjugated to a cellular protein which has a minimum nonreduced molecular weight of approx 55,000 daltons. The dynamics of mescaline incorporation is relatively rapid and the kinetics do not correlate directly with active de novo protein synthesis. Selected inhibitors of oxidation, and metabolic antagonists show no effect on the incorporation of mescaline into protein.     

Slow axoplasmic transport in the hibernating and nonhibernating ground squirrel

Our objectives were to examine the effects of temperature upon slow axoplasmic transport in crushed and intact sciatic nerves of hibernating and nonhibernating ground squirrels (Spermophilus tridecemlineatus). Tritiated leucine was injected into the spinal cord near the ventral horn cells of the sciatic nerve and, after protein incorporation, allowed to transport for 5, 10, 15, or 20 days. Slow transport profiles were obtained from crushed and intact sciatic nerves of hibernating and nonhibernating animals. No significant differences (P < 0.05) were demonstrated in the transport velocities between crushed and noncrushed nerves in either hibernating or nonhibernating ground squirrels. Furthermore, no significant differences were found in transport velocities between hibernating and nonhibernating groups of animals. Slow axoplasmic transport velocities are not only unaffected by crush injury in this system, but also unaffected by normally lethal temperatures. This suggests that the slow component in the nerves of hibernating animals may be responsible for maintaining neurotrophic control throughout hibernation. The data also suggest that different mechanisms may be involved in slow versus fast axoplasmic transport.     

Gut immunity in Lepidopteran insects

Lepidopteran insects constitute one of the largest fractions of animals on earth, but are considered pests in their relationship with man. Key to the success of this order of insects is its ability to digest food and absorb nutrition, which takes place in the midgut. Because environmental microorganisms can easily enter Lepidopteran guts during feeding, the innate immune response guards against pathogenic bacteria, virus and microsporidia that can be devoured with food. Gut immune responses are complicated by both resident gut microbiota and the surrounding peritrophic membrane and are distinct from immune responses in the body cavity, which depend on the function of the fat body and hemocytes. Due to their relevance to agricultural production, studies of Lepidopteran insect midgut and immunity are receiving more attention, and here we summarize gut structures and functions, and discuss how these confer immunity against different microorganisms. It is expected that increased knowledge of Lepidopteran gut immunity may be utilized for pest biological control in the future.     

三氧化二砷对人恶性黑色素瘤A375细胞增殖及新癌基因PPO表达的影响

目的 探讨三氧化二砷对人恶性黑素瘤A375细胞株细胞周期、增殖、凋亡及新癌基因PPO(proliferation and phosphorylation oncogene)表达的影响.方法 培养人恶性黑色素瘤A375细胞株,采用 MTT法检测三氧化二砷在不同浓度和不同时间下对A375细胞增殖的影响,流式细胞术分析三氧化二砷对细胞周期及凋亡的影响,倒置相差显微镜观察药物处理后对人A375细胞的细胞分化及形态的影响,免疫细胞化学(SP)法检测三氧化二砷对PPO蛋白表达的影响.结果 MTT法证实三氧化二砷在1～10 μmol/L浓度范围内对A375细胞有明显的增殖抑制作用,呈现明显的剂量和时间依赖效应关系.流式细胞术检测发现,随着药物浓度的增加,G0/G1的细胞逐渐减少(P＜0.01),S期的比例显著增加,出现S期阻滞.倒置显微镜观察发现细胞出现典型凋亡细胞形态学改变.免疫细胞化学法检测PPO蛋白主要表达于A375细胞胞浆内,染色呈棕黄色.三氧化二砷作用48 h后,随着药物浓度的增加,PPO的染色程度逐渐减弱,差异具有显著性(P＜0.01).结论 三氧化二砷能够显著抑制A375细胞株增殖,并诱导凋亡发生,且与三氧化二砷的浓度和作用时间成正相关,其作用机制可能是通过下调新癌基因PPO的表达发挥作用.     

改性聚苯醚膜对有机混合液的渗透汽化分离

研究了溴代ＰＰＯ地质膜以各种胺化学交联后对氯代烃如氯仿、氯代苯的水溶液的渗透汽化分离性能，以及对甲醇／正戊烷／乙醇／正戊烷等有机液的分离性能。通过和聚乙烯基吡咯烷酮物理共混，提高ＢＰＰＯ膜的极以改善对醇类／正戊烷混合的液的分离选择性。     

ChatGPT:研究进展、模型创新及医学信息研究应用场景优化

目的/意义 梳理分析ChatGPT训练流程与理论模型,为医学研究提供参考借鉴。 方法/过程 系统梳理2018年以来GPT-1发布至今相关模型和流程文献资料,分析ChatGPT核心流程、理论模型及其创新点。根据现有资料分析ChatGPT预训练监督、自动评估以及强化学习近端策略优化(proximal policy optimization,PPO)模型3个层次技术构成。结合医学研究需求,分析人工智能技术面向医学信息领域应用的优化方向。 结果/结论 ChatGPT技术应用的突破是流程、算法和模型有效组合和不断迭代累积的结果,其模型及研究方法可以应用于医学文献自动化阅读与知识提取、基因研究与疾病风险评估等方面。     

Role of descending spinal pathways in the regulation of adrenal tyrosine hydroxylase.

The effects of hemisection of the spinal cord of rats were studied with respect to (a) the ambient level of tyrosine hydroxylase activity of the adrenals bilaterally and (b) the inducibility of the enzyme when the animal is stressed by immobilization or is treated with repeated injections of apomorphine. Three days after surgery the adrenal of the intact side contained increased enzymatic activity at rest and showed an increased response to immobilization. The reverse occurred for the adrenal gland of the sectioned side. After apomorphine administration induction of the enzyme occurred, but to a smaller extent than in sham-operated animals. As previously shown with other parameters of central sympathetic function, the facilitatory and inhibitory components of descending supraspinal pathways (both ipsi- and contralateral) are involved in the regulation of preganglionic neuronal outflow.     

Measurement of peripheral nerve regeneration in the rat and the effects of pyronin or hypothyroidism

The rate of axonal outgrowth in male Sprague-Dawley rats was estimated after crushing the left hypoglossal nerve. Outgrowth was measured by radioactive labeling of the regenerating axon tips. Pyronin G, a mutagenic dye, did not have any significant effect on the rate of regeneration in the hypoglossal nerve. Hypothyroidism induced by the chemical, pyrazole, significantly depressed the rate of regeneration as much as 32%. I conclude that thyroid hormones are essential for normal rates of regeneration in the hypoglossal nerve.     

The effects of aspirin and other non-steroid anti-inflammatory/analgesic drugs on gastro-intestinal mucus glycoprotein biosynthesis in vivo: relationship to ulcerogenic actions.

Aspirin and certain other ulcerogenic non-steroid antiinflammatory (NSAI) drugs inhibit the incorporation in vivo of [³⁵S]sulphate into the mucus glycoproteins isolated from the gastric mucosa of rats. Some NSAI drugs, which are shown to be relatively non-ulcerogenic in a sensitive gastric ulcer assay and the analgesic drugs paracetamol and dextropropoxyphene (which are non-ulcerogenic) did not inhibit the biosynthesis of sulphated mucus glycoproteins in vivo. A relationship is therefore shown between the ulcerogenicity of NSAI drugs and the inhibitory effects on gastric mucus biosynthesis. Some potent intestinal ulcerogens (e.g. indomethacin) also inhibit the incorporation of [³⁵S]sulphate into the glycoproteins from the upper intestinal mucosa. Aspirin in contrast stimulates the incorporation of [³⁵S]sulphate into intestinal mucus glycoproteins. The inhibition of the biosynthesis of sulphated gastric mucus glycoproteins by aspirin is shown to (1) depend on the presence of high concentrations of salicylates in the mucosal tissue, (2) be as a consequence of combined inhibitory capacity of aspirin, salicylate and possibly traces of metabolites in the mucosa and (3) be due to an inhibition of the sulphotransferase activity in vitro. Aspirin also inhibits the incorporation into gastric glycoproteins of [¹⁴C]acetate, but not [¹⁴C]threonine, but the effect on [¹⁴C]acetate incorporation may be due to the redistribution of the isotope in vivo.     

Purine nucleoside phosphorylase, a possible histochemical marker for T-cells in man.

A procedure is described for the histochemical detection of purine nucleoside phosphorylase (PNP) activity in circulating lymphocytes of man. The number of PNP-positive cells, as evaluated on smears of Ficoll--Hypaque purified cells, correlated well with the number of E-rosette-forming cells of the same blood samples of healthy and diseased people with normal or abnormal numbers of E-rosettes. In healthy people, the number of PNP-positive cells was within the range of 70-80% of the total lymphocyte population, whilst the corresponding E-rosette-forming cells were scored between 60-75%. Patients with unusually low or high E-rosettes had equally low or high numbers of PNP-reactive cells. More substantial evidence for the presence of PNP activity in T-cells and not in B cells was gathered from experiments in which PNP activity and surface membrane immunoglobulins (SMIg) were simultaneously demonstrated on the same preparation. These results showed, on the one hand, that the bulk of lymphocytes that are reactive for PNP do not reveal SMIg and, on the other hand, that most Ig-bearing cells were unreactive for PNP.