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Microdensitometry. Microdensitometry。
Pub Date : 2020-02-02 DOI: 10.32388/2zzghk
L. Bitensky
Microdensitometry, or microspectrophotometry, is the measurement of the concentration or mass of a chromophore in microscopically defined regions, and is governed by well-established laws of physics. Initially it proved of value in Feulgen cytophotometry of the relative amounts of DNA in individual nuclei of isolated cells. It has now achieved wide applicability to the measurement of cellular biochemical activity by means of stoichiometric chromogenic reactions. The validity of some of these measurements has been confirmed by comparative biochemical and microdensitometric assays. Thus microdensitometry, even of heterogeneously distributed chromophores, can be precise, provided that the technique is operated with due regard to its limitations within the laws of physics. The potential errors include: variation in thickness of tissue sections (path-length); scatter; glare; diffraction; occlusion of light by optically dense particles; and the inhomogeneity error. However, under correct conditions for the cytochemical reactions and for operating the microdensitometer, these potential errors become small or negligible. Thus the highly sensitive cytochemical bioassay of thyrotropin exemplifies the precision that can be achieved by controlled use of microdensitometry.
微密度测定法,或微分光光度测定法,是在显微镜下确定的区域测量发色团的浓度或质量,并受公认的物理定律支配。最初,它被证明在分离细胞的单个细胞核中DNA的相对量的费尔根细胞光度法中有价值。它现已广泛应用于通过化学计量显色反应来测量细胞生化活性。其中一些测量的有效性已被比较生化和微密度测定法证实。因此,微密度测定,即使是分布不均的发色团,也可以是精确的,只要该技术在操作时适当考虑到其在物理定律中的局限性。潜在的误差包括:组织切片厚度的变化(路径长度);散射;眩光;衍射;光被光学致密粒子遮挡;以及非均匀性误差。然而,在细胞化学反应和操作微密度计的正确条件下,这些潜在的误差变得很小或可以忽略不计。因此,高灵敏度的促甲状腺素细胞化学生物测定是通过控制微密度测定法可以达到的精度的例证。
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引用次数: 22
Peptide metabolism. 肽代谢。
Pub Date : 2020-02-02 DOI: 10.32388/v70kdd
Peptide Metabolism modifications of peptides.
肽的代谢修饰。
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引用次数: 0
Cognitive aspects of preverbal social interaction between human infants and adults. 人类婴儿和成人言语前社会互动的认知方面。
Pub Date : 2008-05-30 DOI: 10.1002/9780470720158.CH14
H. Papoušek, M. Papoušek
Our previous studies on learning and on cognitive development in preverbal human infants indicated that motor activity and social interaction played particularly important roles in the cognitive development of infants. Closer analysis has revealed that motor activity and social interaction have some underlying common regulatory mechanisms. These mechanisms can be detected more easily in infants than in older subjects. An attempt to synthesize our observations led us to the concept that there is a fundamental cognitive process in the integration of adaptive behaviour. This concept may help to elucidate the motivational and emotional aspects of social interaction, the role of mothers or other caretakers in their interactions with infants, and the unfavourable effects of early social deprivation of different types on cognitive development. Some of the assumptions on which this concept is based have been corroborated by analyses of adult-infant interaction.
我们之前对学龄前人类婴儿的学习和认知发展的研究表明,运动活动和社会互动在婴儿的认知发展中起着特别重要的作用。进一步的分析表明,运动活动和社会互动具有一些潜在的共同调节机制。这些机制在婴儿身上比在老年人身上更容易被发现。综合我们的观察结果的尝试使我们得出这样一个概念:在适应性行为的整合中存在一个基本的认知过程。这一概念可能有助于阐明社会互动的动机和情感方面,母亲或其他照顾者在与婴儿互动中的作用,以及早期不同类型的社会剥夺对认知发展的不利影响。这一概念所依据的一些假设已被对成人与婴儿互动的分析所证实。
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引用次数: 78
Salmonellosis: in retrospect and prospect. 沙门氏菌病:回顾与展望。
Pub Date : 2008-05-30 DOI: 10.1002/9780470720936.CH10
J. Stephen, T. Wallis, W. Starkey, D. Candy, M. Osborne, S. Haddon
Despite years of study and the accumulation of much potentially relevant information, neither the microbial determinants nor the pathophysiological mechanisms of salmonella-induced enteritis are known with precision. Earlier work is reviewed on the experimental pathology of salmonellosis, the pathophysiology of the disease and the biotyping of salmonella strains in closed rabbit ileal loops. The same strains have been confirmed by us to be (i) invasive and diarrhoeagenic, (ii) invasive and non-diarrhoeagenic, and (iii) non-invasive and non-diarrhoeagenic. At least two mechanisms have been put forward to explain fluid exsorption. One implicates prostaglandins released from polymorphonuclear cells (PMNs) interacting with invading organisms, whereas the second involves salmonella enterotoxin(s). This subject is in a state of confusion and requires clarification. The toxin has been shown by some to bear partial likeness to either cholera toxin (although the evidence is in fact contradictory) or Shiga toxin. Since both 'cholera-like' and 'Shiga-like' toxins are produced by all three biotypes in vitro, production of toxin (of whatever class or subclass) cannot per se be the sole explanation for salmonella-induced fluid secretion. In our experiments the onset of fluid secretion in rabbit ileal loops was coincident with the appearance of large numbers of infiltrating PMNs. We have also shown that organisms from all three biotypes, grown for 6 h in iron-containing but not in iron-deficient media, yielded polymyxin B extracts which are enterotoxic in rabbit ileal loops; culture supernatants were negative. Structural damage occurred to villus tips but not crypts in infected loops, succeeded the onset of fluid secretion, and was not reproduced by polymyxin B enterotoxic extracts. Thus salmonella diarrhoea may be a complex phenomenon with multiple determinants which might include the release of endogenous secretagogues and bacterial enterotoxin(s), if such are shown to be synthesized and released in vivo at appropriate times and in appropriate sites. Structural damage to villus tips leading to shortened villi may also contribute to diarrhoea by altering absorption (tip function)/secretion (crypt function) ratios as well as to the expulsion of those organisms which have not migrated to deeper tissues.
尽管经过多年的研究和积累了许多潜在的相关信息,但沙门氏菌诱发肠炎的微生物决定因素和病理生理机制都没有得到精确的了解。本文综述了沙门氏菌病的实验病理学、该病的病理生理学和封闭兔回肠环中沙门氏菌菌株的生物分型。我们已确认相同的菌株为(i)侵入性和腹泻性,(ii)侵入性和非腹泻性,以及(iii)非侵入性和非腹泻性。至少有两种机制被提出来解释流体的吸收。一种涉及多形核细胞(pmn)释放的前列腺素与入侵生物相互作用,而第二种涉及沙门氏菌肠毒素。这个问题很混乱,需要澄清。一些人已经证明,这种毒素与霍乱毒素(尽管证据实际上是相互矛盾的)或志贺毒素有部分相似之处。由于“霍乱样”和“志贺样”毒素都是由所有三种生物型在体外产生的,毒素的产生(无论何种类别或亚类别)本身不能成为沙门氏菌诱导的液体分泌的唯一解释。在我们的实验中,家兔回肠袢中液体分泌的开始与大量浸润pmn的出现是一致的。我们还表明,所有三种生物型的生物体,在含铁培养基中生长6小时,而不是在缺铁培养基中生长,产生的多粘菌素B提取物在兔回肠袢中具有肠毒性;培养上清为阴性。感染环的绒毛尖端发生结构损伤,而隐窝未发生结构损伤,在液体分泌开始后发生结构损伤,多粘菌素B肠毒性提取物不能复制结构损伤。因此,沙门氏菌腹泻可能是一个复杂的现象,有多种决定因素,其中可能包括内源性分泌物和细菌肠毒素的释放,如果这些被证明是在适当的时间和适当的地点在体内合成和释放的话。绒毛尖端的结构损伤导致绒毛缩短,也可能通过改变吸收(尖端功能)/分泌(隐窝功能)的比例,以及排出那些尚未迁移到深层组织的生物,从而导致腹泻。
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引用次数: 36
Evaluation of modern foods as sources of lipids. In: lipids, malnutrition & the developing brain. 现代食品作为脂质来源的评价。错误:脂质,营养不良和大脑发育。
Pub Date : 2008-05-30 DOI: 10.1002/9780470719862.CH13
U. Houtsmuller
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引用次数: 0
Local and collective motions in protein dynamics. 蛋白质动力学中的局部运动和集体运动。
Pub Date : 2008-05-30 DOI: 10.1002/9780470720752.CH15
M. Karplus, S. Swaminathan, T. Ichiye, W. V. van Gunsteren
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引用次数: 5
The 'see-saw' theory of parturition. 分娩的“跷跷板”理论。
Pub Date : 2008-05-30 DOI: 10.1002/9780470720295.CH8
A. Csapo
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引用次数: 104
Local calcium spiking in pancreatic acinar cells. 胰腺腺泡细胞的局部钙峰值。
Pub Date : 2007-09-28 DOI: 10.1002/9780470514696.CH6
O. Petersen
A few years ago, my laboratory obtained evidence for local agonist-evoked repetitive Ca2+ spikes in single pancreatic acinar cells. We have now confirmed this and shown that regular cytosolic Ca2+ spikes evoked by low concentrations of acetylcholine or inositol 1,4,5-trisphosphate (InsP3) are confined to the secretory granule area at the luminal pole of the cells. The local subcellular signals probably arise because the first internal messenger (InsP3), generated from the basolateral membrane, can diffuse rapidly, whereas the Ca2+ released from the more responsive secretory granule region has a very restricted mobility. Local Ca2+ spikes are useful from an energetic point of view and also help to avoid undesirable activation of Ca(2+)-dependent processes. Another messenger, cyclic ADP-ribose, may also regulate intracellular Ca2+ release. In pancreatic acinar cells cyclic ADP-ribose induces repetitive Ca2+ spikes localized in the secretory granule area; these spikes are blocked by ryanodine, but also by the InsP3 receptor antagonist heparin. Ryanodine abolishes or markedly inhibits agonist-evoked Ca2+ spiking, but enhances the frequency of spikes evoked by internal InsP3 application. These results indicate that both ryanodine and InsP3 receptors are involved in Ca2+ spike generation in pancreatic acinar cells, and that both InsP3 and cyclic ADP-ribose may act as internal messengers.
几年前,我的实验室在单个胰腺腺泡细胞中获得了局部激动剂诱发的重复Ca2+峰值的证据。我们现在已经证实了这一点,并表明由低浓度的乙酰胆碱或肌醇1,4,5-三磷酸(InsP3)引起的有规律的胞质Ca2+峰值被限制在细胞腔极的分泌颗粒区域。局部亚细胞信号的产生可能是因为基底外侧膜产生的第一个内部信使(InsP3)可以迅速扩散,而从更敏感的分泌颗粒区释放的Ca2+的流动性非常有限。从能量的角度来看,局部Ca2+尖峰是有用的,也有助于避免Ca(2+)依赖过程的不良激活。另一个信使,环adp核糖,也可能调节细胞内Ca2+的释放。在胰腺腺泡细胞中,环状adp核糖诱导位于分泌颗粒区域的重复Ca2+尖峰;这些尖峰可以被良诺定阻断,也可以被InsP3受体拮抗剂肝素阻断。Ryanodine消除或显著抑制激动剂引起的Ca2+尖峰,但增加了内部应用InsP3引起的尖峰频率。这些结果表明,ryanodine和InsP3受体都参与了胰腺腺泡细胞Ca2+尖峰的产生,并且InsP3和环adp核糖都可能作为内部信使。
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引用次数: 14
Turnover and metabolism of hyaluronan. 透明质酸的周转和代谢。
Pub Date : 2007-09-28 DOI: 10.1002/9780470513774.CH4
J. Fraser, T. Laurent
The highest concentrations of hyaluronan occur in synovial fluid, vitreous body, skin and certain specialized tissues such as umbilical cord and rooster comb, during fetal development, and in tissue repair and regeneration. The largest amounts are found in the intercellular matrix of skin and musculoskeletal tissues. Turnover in the bloodstream is normally in the range of 0.3-1.0 microgram min-1/kg body weight. Circulating hyaluronan is mostly derived from lymph. Lymph nodes may nevertheless extract as much as 80-90% from peripheral lymph before it can reach the bloodstream. Turnover in peripheral tissues may be effected by degradation in situ, or by transfer into lymph by diffusion or hydrodynamic forces. Hyaluronan is firmly bound in specific association with cells or binding proteins but much of it exists in freely mobilized compartments with a half-life of two days or less, and it is metabolized after transport elsewhere. Metabolic degradation of hyaluronan is principally intracellular and relies on uptake by a receptor which, in contrast with other hyaluronan-binding structures, also binds chondroitin sulphate. It is suggested that this dual specificity may be primarily associated with metabolic degradation of hyaluronan. Uptake and metabolism are primarily effected in liver and lymph node by endothelial cells lining the sinusoids of each. Further studies indicate that in lymph nodes and in spleen, macrophage-like cells intertwined with the endothelial cells also take up hyaluronan. The metabolic cycle from polymer to monosaccharides, acetate and beyond can be completed in vivo within 10 minutes.
透明质酸的最高浓度出现在滑液、玻璃体、皮肤和某些特殊组织,如脐带和鸡冠,在胎儿发育期间,以及在组织修复和再生中。在皮肤和肌肉骨骼组织的细胞间基质中发现的量最大。血液中的周转量通常在0.3-1.0微克/千克体重之间。循环透明质酸主要来自淋巴。然而,在周围淋巴到达血液之前,淋巴结可以从周围淋巴中提取80-90%。外周组织的转化可能受到原位降解或通过扩散或流体动力转移到淋巴的影响。透明质酸与细胞或结合蛋白紧密结合,但大部分存在于半衰期为两天或更短的自由活动的腔室中,并在运输到其他地方后代谢。透明质酸的代谢降解主要发生在细胞内,依赖于受体的摄取,与其他透明质酸结合结构不同,该受体也结合硫酸软骨素。这种双重特异性可能主要与透明质酸的代谢降解有关。摄取和代谢主要是在肝脏和淋巴结由内皮细胞衬里的鼻窦。进一步研究表明,在淋巴结和脾脏中,与内皮细胞交织的巨噬细胞样细胞也摄取透明质酸。在体内,从聚合物到单糖、乙酸酯等的代谢循环可在10分钟内完成。
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引用次数: 211
Prion protein amyloid: separation of scrapie infectivity from PrP polymers. 朊蛋白淀粉样蛋白:从PrP聚合物中分离痒病传染性。
Pub Date : 2007-09-28 DOI: 10.1002/9780470514924.CH12
H. Wille, M. Baldwin, F. Cohen, S. DeArmond, S. Prusiner
The prion protein (PrP) undergoes a profound conformational change when the cellular isoform (PrPc) is converted into the scrapie form (PrPSc). Limited proteolysis of PrPSc produces PrP27-30 which readily polymerizes into amyloid. To study the structure of PrP amyloid, we employed organic solvents that perturb protein conformation. 1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP), which promotes alpha-helix formation, modified the ultrastructure of rod-shaped PrP amyloids, producing flattened ribbons with a more regular substructure. As the concentration of HFIP was increased, the beta-sheet content and proteinase K resistance of PrP27-30 as well as prion infectivity diminished. HFIP reversibly decreased the binding of Congo red dye to the rods, whereas inactivation of prion infectivity was irreversible. In contrast to 10% HFIP, 1,1,1-trifluoro-2-propanol (TFIP) did not inactivate prion infectivity but, similarly to HFIP, TFIP did alter the morphology of the rods and abolished Congo red binding. Our studies separate prion infectivity from the amyloid properties of PrP27-30 and underscore the dependence of prion infectivity on PrPSc conformation. Our results also demonstrate that the specific beta-sheet-rich structures required for prion infectivity are different from those needed for amyloid formation.
朊病毒蛋白(PrP)在细胞异构体(PrPc)转化为痒病蛋白(PrPSc)时发生了深刻的构象变化。有限的PrPSc蛋白水解产生PrP27-30,它很容易聚合成淀粉样蛋白。为了研究PrP淀粉样蛋白的结构,我们使用了干扰蛋白质构象的有机溶剂。1,1,1,3,3,3-六氟-2-丙醇(HFIP)可以促进α -螺旋的形成,改变棒状PrP淀粉样蛋白的超微结构,产生具有更规则亚结构的扁平带。随着HFIP浓度的增加,PrP27-30的β -sheet含量、蛋白酶K抗性和朊病毒感染性降低。HFIP可逆地降低了刚果红染料与杆状细胞的结合,而朊病毒的传染性失活是不可逆的。与10% HFIP相比,1,1,1-三氟-2-丙醇(TFIP)没有灭活朊病毒的感染性,但与HFIP相似,TFIP确实改变了杆状体的形态并消除了刚果红结合。我们的研究将朊病毒的感染性从PrP27-30的淀粉样蛋白特性中分离出来,并强调了朊病毒的感染性对PrPSc构象的依赖性。我们的研究结果还表明,朊病毒感染性所需的特异性-富β -薄片结构与淀粉样蛋白形成所需的结构不同。
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引用次数: 8
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Ciba Foundation symposium
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