PET-CT在非完全实性肺结节中的应用价值

肺癌在中国恶性肿瘤的发病率位居第一,随着低剂量薄层CT在肺癌筛查中的广泛应用,临床发现更多表现为非完全实性结节的肺腺癌,目前众多研究使CT影像学特征和肺腺癌病理的关系得到更进一步的认知,虽然CT能对部分非完全实性结节做出定性和定位诊断,但仍有部分非完全实性结节诊断困难,PET-CT结合了病灶的代谢信息和精确的定位信息,从而提高对肺部结节诊断的敏感性、特异性、准确性,综合多个文献PET-CT在非完全实性结节中的诊断分期价值较CT无明显提升,却在评估预后和制定合适手术方案上可以起到一定的作用,本文就PET-CT在SSN中的应用价值进行阐述。     

Mode of action of ergonovine on isolated porcine coronary artery: the role of Ca2+

Coronary vasoconstrictor responses to ergonovine were examined in helical coronary arterial strips of young swine. Both ergonovine and serotonin (5-hydroxytryptamine) produced dose-dependent contractions of the strips. The distal region (less than 1.00 mm outer diameter) of the circumflex coronary artery was most sensitive to the responses of serotonin and ergonovine. Methysergide and nifedipine significantly depressed the contractions induced by ergonovine and serotonin. Atropine, propranolol, and the alpha 1 blocker, prazosin, did not antagonize ergonovine-induced contractions. The ergonovine response may depend entirely upon extracellular Ca2+ while the effect of serotonin may be mediated in part through the mobilization of intracellular Ca2+ stores. Increases in 45Ca2+ cellular contents occurred after ergonovine or serotonin and these increases were blocked by methysergide or nifedipine at concentrations which blocked mechanical responses to the agonist. It is concluded that the contractions of the porcine coronary artery produced by ergonovine and serotonin are as follows: (i) regionally sensitive; (ii) blocked by Ca2+ antagonists and therefore may utilize Ca2+ channels similar to those described in other excitable tissues; (iii) blocked by methysergide. These studies indicate that the major mechanism of ergonovine's action in the porcine coronary artery is through the activation of serotonin receptors on coronary arteries which are, in turn, linked to Ca2+ channels. However, this mechanism of action may be different in an intact animal.     

Evolution of feeding niches in New World monkeys.

The adaptive radiation of modern New World monkeys unfolded as the major lineages diversified within different dietary-adaptive zones predicated upon a fundamentally frugivorous habit. The broad outlines of this pattern can be seen in the fossil record, beginning in the early Miocene. Cebids are obligate frugivorous predators. The smallest forms (Cebuella, Callithrix) are specialized exudativores, and the largest (cebines) are seasonally flexible omnivores, feeding particularly on insects (Saimiri) or "hard" foods, such as pith and palm nuts (Cebus), when resources are scarce. The smaller-bodied atelids (Callicebus, Aotus) may use insects or leaves opportunistically, but pitheciins (saki-uakaris) specialize on seeds as their major protein source. The larger atelines (Alouatta, Brachyteles) depend on leaves or on ripe fruit (Ateles). Locomotion, body size, and dietary adaptations are linked: claws and small body size opened the canopy-subcanopy niche to callitrichines; climbing and hanging, the fine-branch setting to the atelines; large size and strength, semiprehensile tails, and grasping thumbs, the extractive insectivory of Cebus; deliberate quadrupedalism, the energy-saving transport of folivorous Alouatta. Body size increases and decreases occurred often and in parallel within guilds and lineages. Conventional dietary categories, particularly frugivory, are inadequate for organizing the behavioral and anatomical evidence pertinent to evolutionary adaptation. Related models of morphological evolution based on feeding frequencies tend to obfuscate the selective importance of "critical functions," responses to the biomechanically challenging components of diet that may be determined by a numerically small, or seasonal, dietary fraction. For fossils, body size is an unreliable indicator of diet in the absence of detailed morphological information. More attention needs to be given to developing techniques for identifying and quantifying mechanically significant aspects of dental form, the physical properties of primate foods, their mode of access, and the cycles of availability and nutritional value.     

Design considerations for two-stage enrichment clinical trials

When there is a predictive biomarker, enrichment can focus the clinical trial on a benefiting subpopulation. We describe a two-stage enrichment design, in which the first stage is designed to efficiently estimate a threshold and the second stage is a “phase III-like” trial on the enriched population. The goal of this paper is to explore design issues: sample size in Stages 1 and 2, and re-estimation of the Stage 2 sample size following Stage 1. By treating these as separate trials, we can gain insight into how the predictive nature of the biomarker specifically impacts the sample size. We also show that failure to adequately estimate the threshold can have disastrous consequences in the second stage. While any bivariate model could be used, we assume a continuous outcome and continuous biomarker, described by a bivariate normal model. The correlation coefficient between the outcome and biomarker is the key to understanding the behavior of the design, both for predictive and prognostic biomarkers. Through a series of simulations we illustrate the impact of model misspecification, consequences of poor threshold estimation, and requisite sample sizes that depend on the predictive nature of the biomarker. Such insight should be helpful in understanding and designing enrichment trials.     

Cell attachment to collagen: The ionic requirements

This study is concerned with three aspects of the ionic requirements for cell attachment to collagen; namely (a) the divalent, (b) monovalent cation specificities and (c) pH optima for cell interaction with collagen. The divalent cation requirement for cell attachment to collagen can be sufficed by Ca²⁺, Mg²⁺ and certain transition group metals; whereas Ba²⁺, Sr²⁺, and polyamines are inactive. The pH optimum for cell attachment in this system occurs in the physiological range. The monovalent cation requirement for cell attachment to collagen is satisfied by isotonic NaCl, KCl, LiCl, NH₄Cl, sucrose, and glucose. Pronounced inhibition of cell attachment occurs under both hypertonic and hypotonic conditions.     

Distribution of autolysins in hyphae of Aspergillus nidulans: evidence for a lipid-mediated attachment to hyphal walls.

Preparations of broken Aspergillus nidulans hyphae contained both free and wall-bound autolysins. The bound enzymes were not solubilized by 8 M LiCl or neutral or anionic detergents; they were readily detached from walls by a cationic detergent or by autodigestion. Once detached, the enzymes did not reassociate with wall to give salt-resistant complexes. Six enzymes hydrolyzing wall polymers were bound to the envelope, and the same activities were also detected among soluble proteins in the cytoplasmic fraction. It is suggested that cytoplasmic vesicles, containing autolysins, are inserted into or trapped by newly formed wall in the growing hypha; these constitute the wall-bound autolysin fraction. Starvation for a carbon source derepressed the synthesis of five out of the six autolysins, and the amounts of both soluble and wall-bound activities increased by one to two orders of magnitude.     

Carbohydrate preferences of mammalian cells.

Carbohydrate preferences of mammalian cells can be utilized to biochemically distinguish between different cell lines. Ninety-three carbohydrates were examined of which (a) 15 supported cell proliferation and (b) 42 were toxic or growth inhibitory. The present investigation has employed an enzymatic system to eliminate trace glucose levels from reagents and glucose generated by serum enzymes.     

Determination of the execution points of mutations in the nuclear replication cycle of Aspergillus nidulans.

Cultures of nuclear replication cycle mutants of Aspergillus nidulans were transferred to the nonpermissive temperature, and the fraction of nuclei still able to reach mitosis was determined. For the determinations, benomyl [methyl-1(butylcarbomoyl)benzimidazolecarbamate] was added to trap nuclei in mitosis, and these were detected by staining with aceto-orcein. The assumptions and controls required to relate the experimentally determined fractions to the points where a mutation blocks the nuclear cycle are discussed. Nine genetically distinct mutants were tested. Two of these were blocked early in the cycle, two in the middle, and five close to, or during, mitosis.     

烟青虫感染核型多角体病毒后围食膜的病变

昆虫的围食膜是衬在昆虫中肠内一种网状的结构,它可充作虫体抵御外来病原侵染的一道屏障。关于鳞翅目昆虫幼虫感染了昆虫病毒后围食膜的病变问题,国内外鲜有报道。尤锡镇和康慧娟(1985)曾以实验证明家蚕围食膜对核型多角体病毒有灭活作用,而且认为核型多角体病毒不能侵染和破坏围食膜。Derksen和Granados(1988)则证明染病幼虫的围食膜因不同杆状病毒(包括两种核型多角体病     

κ-卡拉胶琥珀酰基化衍生物的抗氧化活性研究

对κ-卡拉胶进行酸降解得到三种卡拉胶低聚糖,并进一步琥珀酰基化得到分子量分别为2720、4000和5960的κ-卡拉胶琥珀酰衍生物(A、B和C)。对产物进行FT-IR表征,并测得其琥珀酰基取代度(DS)分别为0.61、0.29和0.83。检测了三种κ-卡拉胶琥珀酰衍生物对超氧阴离子自由基O2.-、DPPH自由基、羟基自由基.OH以及过氧化氢的清除活性。结果表明:随着取代度的增加,其清除超氧阴离子自由基O2.-和DPPH自由基的能力增强;随着分子量的增加,其清除羟基自由基.OH和过氧化氢的能力增强。这可能与衍生物的羟基含量、取代基团的性质以及取代度等因素有关。