Comment on the applicability of compartment theory to interacting biochemical systems

Riassunto Viene tratteggiata riassuntivamente l'impostazione matematica del problema dell'interazione fra più sistemi a compartimenti.     

Cooperation between the two myosin heads interacting with actin in presence of ADP in myofibrils

Zusammenfassung Alkylierung von 2 Thiolgruppen pro Myosin mit NEM bei 0°C in Gegenwart einer Diophosphatkette inaktiviert die K-ATPase vollständig.In Myofibrillen werden diese Thiolgruppen durch Rigor-interaction beider Myosinköpfchen mit Actin vor Alkylierung geschützt. In Gegenwart von Mg-ADP tritt eine spezifische vom Rigor verschiedene interaction zwischen Myosin und Actin auf. Man muss annehemen, dass dabei nur 1 Myosinköpfchen ans Actin bindet und dass das andere Köpfchen ein ADP gebunden hat.     

External synchronization of two dynamical systems with uncertain parameters

External synchronization is addressed as two or more dynamical systems with synchronous motions, which is also regarded as master-slave system. In this paper, two dynamical systems, one employs a hysteretic term to model the friction phenomenon, the other involves a hardening stiffness component with the third order of displacement due to flexible deformation, are controlled to converge to the same trajectory. The control strategy is extended from feedback control for all parameters known to adaptive contro...     

Pre- and postnatal distribution of lipids in the liver of genetic diabetic mice.

Triglycerides, phospholipids, cholesterol and cholesterol esters were determined by thin layer chromatography in the fetal and neonate livers of normal (Swiss albino) and genetic diabetic (KK) mice. In general, the lipids were elevated in the fetal liver of the KK mice. Despite this elevation in liver lipids, no increase in the weight of the newborn was observed.     

Periostin and its interacting proteins in the construction of extracellular architectures

Periostin is a matricellular protein that is composed of a multi-domain structure with an amino-terminal EMI domain, a tandem repeat of four FAS 1 domains, and a carboxyl-terminal domain. These distinct domains have been demonstrated to bind to many proteins including extracellular matrix proteins (Collagen type I and V, fibronectin, tenascin, and laminin), matricellular proteins (CCN3 and βig-h3), and enzymes that catalyze covalent crosslinking between extracellular matrix proteins (lysyl oxidase and BMP-1). Adjacent binding sites on periostin have been suggested to put the interacting proteins in close proximity, promoting intermolecular interactions between each protein, and leading to their assembly into extracellular architectures. These extracellular architectures determine the mechanochemical properties of connective tissues, in which periostin plays an important role in physiological homeostasis and disease progression. In this review, we introduce the proteins that interact with periostin, and discuss how the multi-domain structure of periostin functions as a scaffold for the assembly of interacting proteins, and how it underlies construction of highly sophisticated extracellular architectures.     

Effects of Pre- and simultaneous treatment with urea on the induction of chromatid aberrations inVicia faba

Summary Pre- and simultaneous treatments ofVicia faba root tip meristems with urea and ethyl alcohol, mitomycin C, maleic hydrazide,³H-thymidine and X-rays, respectively, were found to result in mutagen-specific changes of the spectrum and yield of induced chromatid aberrations.     

Intracellular pH of Limulus ventral photoreceptor measured with a double-barrelled pH microelectrode

Summary The intracellular pH of the Limulus ventral photoreceptor was measured with a double-barrelled pH microelectrode and found to be 7.01±0.04 SE (n=9).This work was supported by the Swiss National Science Foundation, grants Nos. 3.634.075 and 3.128.73.Acknowledgments. We thank Drs L. R. Pucacco and N. W. Carter for technical advice and a gift of pH glass. We also thank Drs M. Tsacopoulos and F. Baumann for helpful discussion.     

电位-pH图及其研究进展

阐述了电位-pH图的意义及应用,比较了绘制理论电位-pH图和实验电位-pH图的优劣,着重阐述了理论电位-pH图的绘制步骤及方法,列出了与电位-pH图绘制有关的4类反应。概述了人们在生成热力学稳定区一优势区（Predominance area phase diagram）的算法上的发展过程。联系当今科学研究及生产的需要,探讨了今后电位-pH图研究的重点和方向。     

Effect of light and pH on diazotized bilirubin

Zusammenfassung Die Wirkung normaler Raumbelichtung (elektrisches fluoreszierendes Licht) und diejenige der Wasserstoffionen-Konzentration auf diazotiertes Bilirubin wurde untersucht. Während elektrisches Licht bei den gegebenen Versuchsbedingungen zu keiner Änderung der optischen Dichte führte, bewirkte ein Zusatz von Natronlauge eine Verminderung der optischen Dichte und zwar unbeeinflusst durch den Zusatz von HCL.     

Long term stability of lysine vasopressin and of specifically tritiated lysine vasopressin in weakly acidic aqueous solutions

Summary Lysine vasopressin tritiated at meta position of tyrosine (1.9 Ci/mmole) decomposes during a long storage period, mainly as a result of radiolysis. The loss of specific activity by isotopic exchange with water is slow. The nonlabelled peptide undergoes only very minute decomposition (polymerization). Specific radioactivity declines with a half life of 47.4 months.Acknowledgments. This research was supported by Swiss National Science Foundation, grant No.3.040.76 (V.P.). Some of the measurements (years 1969–70) were carried out at Roche Institute of Molecular Biology, Nutley, N.J., USA.     

Double pH optima of potato invertase

Zusammenfassung Kartoffelinvertase scheint zwei pH-Optima zu haben; ein Optimum bei pH 6 und das andere bei oder unterhalb pH 3,5. Es scheint evident, dass das Phänomen nicht mit dem Vorhandensein von zwei Enzymen zusammenhängt. Untersuchungen über die Kinetik des Enzyms lassen daran denken, dass das doppelte pH-Optimum mit einer amphoteren Hemmungssubstanz der Invertase in Beziehung steht.     

Amyloid precursor protein products concentrate in a subset of exosomes specifically endocytosed by neurons

Amyloid beta peptide (Aβ), the main component of senile plaques of Alzheimer’s disease brains, is produced by sequential cleavage of amyloid precursor protein (APP) and of its C-terminal fragments (CTFs). An unanswered question is how amyloidogenic peptides spread throughout the brain during the course of the disease. Here, we show that small lipid vesicles called exosomes, secreted in the extracellular milieu by cortical neurons, carry endogenous APP and are strikingly enriched in CTF-α and the newly characterized CTF-η. Exosomes from N2a cells expressing human APP with the autosomal dominant Swedish mutation contain Aβ peptides as well as CTF-α and CTF-η, while those from cells expressing the non-mutated form of APP only contain CTF-α and CTF-η. APP and CTFs are sorted into a subset of exosomes which lack the tetraspanin CD63 and specifically bind to dendrites of neurons, unlike exosomes carrying CD63 which bind to both neurons and glial cells. Thus, neuroblastoma cells secrete distinct populations of exosomes carrying different cargoes and targeting specific cell types. APP-carrying exosomes can be endocytosed by receiving cells, allowing the processing of APP acquired by exosomes to give rise to the APP intracellular domain (AICD). Thus, our results show for the first time that neuronal exosomes may indeed act as vehicles for the intercellular transport of APP and its catabolites.     

Purification and stability of specifically tritium labelled lysine vasopressin (Tyrosine2-3-T-lysine8-vasopressin)

Zusammenfassung Tyrosin²-3-T-Lysin⁸-Vasopressin, das vor 2 1/2 Jahren synthetisiert worden war, wurde auf CM-Sephadex-C-25-Säulen gereinigt. Die spezifische Radioaktivität des spezifisch markierten Hormons war nur auf 80% gefallen, was einen verhältnismässig kleinen Grad von Isotopaustausch für das Nonapeptid selber anzeigt.     

The pH as controlling factor of shape and function of mitochondria

Riassunto È stato osservato che quando il pH intra-cellulare è più basso di quello plasmatico la forma dei mitocondri è prevalentemente a bastoncino, aumentando il pH (in condizioni sperimentali e patologiche) i mitocondri tendono a rigonfiare. Il fenomeno è anche dimostrabile spettrofotometricamente sui mitocondri isolati il cui rigonfiamento spontaneo regredisce abbassando il pH del mezzo. Il QO₂(N) e l'attività ATPasica aumentano a pH alcalini parallelamente al rigonfiamento mitocondriale. Il rapporto P/O si mantiene accoppiato fra pH compresi fra 6.6 e 7.4.È possibile che attraverso il pH si verifichi nella cellula un meccanismo di autoregolazione dell'attività funzionale dei mitocondri.