Showing papers by "University of Geneva published in 1971"

Presence of modified fibroblasts in granulation tissue and their possible role in wound contraction.

Abstract: Au cours de la contraction du tissu de granulation, de nombreux fibroblastes acquierent des caracteristiques ultrastructurelles qui les rendent semblables a des cellules musculaires lisses. Il est probable que ces elements modifies jouent un role dans le processus de contraction des plaies.

Contraction of granulation tissue in vitro: similarity to smooth muscle

Abstract: Strips of granulation tissue from three different experimental models contract in vitro when treated with substances that induce contraction of smooth muscle. Because the fibroblasts in such tissues have some ultrastructural features typical of smooth muscle, our findings indicate that fibroblasts are able to modulate toward a cell type that is morphologically and functionally close to smooth muscle.

Properties of dual multiloop amplitudes

Abstract: Previous results on the dual multiloop amplitude are extended by obtaining, from the unitarization procedure, the measure and domain of integration. The singularities of the amplitude, which arise from end points in the integration domain, are discussed by exploiting the simple geometrical interpretation of the theory. In particular, we investigate the singularities which give rise to divergences in planar diagrams as well as Pomeranchuk-like singularities in nonplanar ones.

Primary Induction in Birds

Abstract: Publisher Summary This chapter discusses the phenomenon of embryonic induction. This phenomenon was discovered in amphibians. This group of vertebrates is the best suited for the analysis of various aspects of the induction phenomenon. In amniotes, especially birds, an analysis of the primary induction, beyond the pure morphological description, encounters serious technical obstacles. Young blastoderms are sensitive to simple operations performed in ovo . Even a simple puncture of the eggshell and an incision made in the vitelline membrane often result in severe abnormalities as well as precocious death. Most of the experiments carried out consist either of the transplantation of grafts in blastoderms cultured in vitro or of the explantation of sandwich-type grafts in the coelomic cavity. At the early stages of their development, the germ wall of the blastoderm phagocytoses the yolk necessary for the nutrition of the blastoderm. Therefore, in vitro culture involving isolation of the blastoderm from the natural yolk substratum cannot be carried out for long periods. Cellular differentiation can be observed when the induced fragments are grafted and allowed to develop in the coelomic cavity of older embryos. In these conditions, the morphology of the induced structures is atypical and an identification of their regional characteristics is possible based on histological criteria.

Fibroblasts of granulation tissue: immunofluorescent staining with antismooth muscle serum

Abstract: SummaryHuman antibody against smooth muscle such as found in patients with autoimmune hepatitis binds to rat fibroblasts in contracting granulation tissue, but not to normal rat fibroblasts. This p...

Inhibition of RNA polymerase by streptolydigin.

Abstract: The antibiotic streptolydigin inhibits RNA polymerase by reducing the rate of RNA chain growth. It does not affect the fidelity of transcription.

Synovial sarcoma. Electron microscopic study of a typical case.

Abstract: A case of histologically typical synovial sarcoma has been studied by means of electron microscopy. The more important findings are: 1. the confirmation at the ultrastructural level of the biphasic pattern of the tumor; 2. the presence of a basal lamina between the “epithelial” and the “stromal” part of the tumor; 3. the presence of specialized junctions in the form of desmosomes or maculae adhaerentes between neoplastic cells; these are mostly seen in the epithelial part of the tumor but are not infrequent among stromal cells, and 4. the existence in the extracellular component of the neoplasm of mostly amorphous material, microfibrils, and thin fibrils without periodicity. Only a few mature collagen fibers are seen.

Temporal Relationships in Language

Abstract: Bref expose d'une approche piagedenne a l'etude de l'acquisition du langage. Certains principes de base de la psychologie genetique qui s'appliquent egalement a ce domaine sont rappeles. La methode d'interrogadon qui en decoule est presentee ainsi que les raisons qui ont amene les auteurs a envisager l'etude de l'acquisition de certaines structurations linguistiques a travers des epreuves de comprehension, de production et de repetition. La technique a pour but de saisir les changements qualitatifs dans les reponses des enfants (de 4 a 9 ans), dont on conna[icaron]t le niveau de developpement cognitif, determine par des epreuves propres a la psychologie genetique. A titre d'exemple une recherche recente est brievement discutee. Elle porte sur la comprehension, la production et la repetition de phrases qui expriment une relation d'ordre temporel entre deux evenements. L'accent est mis sur les resultats obtenus dans les epreuves de production qui sont les plus revelateurs du mode d'elaboration de c...

The metabolism of L‐3–0‐methyldopa, aprecursor of dopa in man

Abstract: L-2-14C-3-methoxy, 4-hydroxyphenylalanine (L-14C-O-methyldopa) has a biological half-life of approximately 15 hours in human blood. 3-Methoxy, 4-hydroxyphenyllactic acid, homovanillic acid, and 3,4-dihydroxyphenylacetic acid are metabolites found in the blood. The urinary excretion of radioactivity is slow and only a small proportion of excreted radioactivity represents unchanged O-methyldopa. The same metabolites are found as in the blood as weU as small amounts of dopa, dopamine, and 3-methoxytyramine. It is concluded that in man part of the L-O-methyldopa undergoes demethylation to dopa, which is further metabolized to dopamine and phenolcarboxylic acids.

Spontaneous hyperglycemia and-or obesity in laboratory rodents: an example of the possible usefulness of animal disease models with both genetic and environmental components.

Abstract: Publisher Summary This chapter provides an overview of spontaneous hyperglycemia and/or obesity in laboratory rodents. In considering the spontaneously occurring hyperglycemic syndromes of laboratory animals as they relate to understanding the pathogenesis of human diabetes, it is emphasized that no single animal syndrome can yet be considered the exact or even the best model for human diabetes. Further extensive study of the available animal strains may prove to be extremely useful. Observations related to the heredity of the syndromes emphasize the need for caution in considering any theory of the pathogenesis of diabetes based on a single and genetically simple anomaly. The secretion of excessive amounts of insulin appears to be the earliest discernible anomaly. Insulin resistance may be the cause of the enhancement of insulin release in those animal strains in which environmental manipulation has resulted in an increase in caloric intake.

Zinkblende- und Wurtzitüberstrukturen bei ternären Chalkogeniden der Zusammensetzung 12463

Abstract: Fruhere Literaturangaben uber die Struktur von Cu2GeSe3 und der Tieftemperaturmodifikation von Cu2GeS3 wurden als unrichtig befunden. Beide Verbindungen kristallisieren in einer orthorhombischen Zinkblendeuberstruktur mit 2 Formeleinheiten pro Zelle (Raumgruppe Imm2). Die Punktpositionen fur Cu2GeSe3 wurden erhalten unter Verwendung von Einkristallintensitaten, die auf einem automatischen Diffraktometer gemessen wurden. Eine orthorhombische Wurtzituberstruktur wurde bei der Hochtemperaturmodifikation von Cu2SiS3 aufgefunden (Raumgruppe Cmc21 mit 4 Formeleinheiten pro Zelle). Die beiden neuen Strukturen gehoren zu den normal tetraedrischen Strukturen und konnten entsprechend den Tetraederstrukturregeln nicht nur bei 12463−, sondern auch bei 14253− Verbindungen auftreten.

Superconductivity, density-of-states models, and specific heat of A15-type compounds V--Ga and V--Si

Abstract: Accurate low-temperature specific heat measurements, together with structural investigations, have been performed in V-Ga alloys with 18–32% Ga and V-Si alloys with 20–27% Si. Calculations of the temperature dependence of the normal electronic specific heat are presented for different band models. The comparison with experiment suggests that very low degeneracy temperatures are indeed characteristic of both V3Ga and V3Si.

Aorto-coronary by-pass with autogenous saphenous vein grafts: histopathological aspects.

Abstract: The histological modifications in 8 cases of autologous aorto-coronary saphenous vein grafts were studied. In the early stages, these showed intimal thickening and medial hypertrophy, particularly affecting the middle circular layer. The intimal thickening progressed, and the media later became largely replaced by dense fibrous tissue. No aneurysmal dilatations were observed, but in 3 cases the grafts were thrombosed. The pathogenesis of these changes is discussed.

Agrobacterium tumefaciens Ribonucleic Acid Synthesis in Tomato Cells and Crown Gall Induction

Abstract: Purified Agrobacterium tumefaciens deoxyribonucleic acid (DNA) does not produce crown gall tumors in growing plants, conditioned by wounding, as the living bacteria do. Purified bacterial DNA migrates in the plant and replicates, but it is not transcribed in our experimental conditions. On the contrary, when DNA is released naturally from bacteria into plant cells, a bacterial ribonucleic acid (RNA) can be found in these cells. There seems to be a direct relation between the appearance of A. tumefaciens RNA in the plant cells and the induction of the tumor.

MORPHOLOGICAL AND BIOCHEMICAL STUDIES OF B CELLS OF FETAL RAT ENDOCRINE PANCREAS IN ORGAN CULTURE : Evidence for (Pro)Insulin Biosynthesis

Abstract: Fetal rat pancreases explanted on the 18th day of gestation and maintained in organ culture for 1–10 days were utilized for this series of studies. Ultrastructurally, at the time of explantation, the majority of fetal B cells was sparsely granulated and characterized by numerous free ribosomes and undeveloped rough endoplasmic reticulum (RER) and Golgi complexes. During the culture period, extensive development of the RER and Golgi complexes preceded an increasing accumulation of β-granules. This later increase in the number of β-granules and in the concentration of immunoreactive insulin was paralleled by a reduction of RER and Golgi complex activity. High resolution radioautographic studies of pulse-chase experiment over a 1 hr period demonstrated the shift of silver grains from the elements of the RER, through the Golgi region, and finally to the β-granules. Incubation with 14C-labeled leucine demonstrated the incorporation of radioactivity into molecules possessing the immunological and electrophoretic properties of insulin. These studies indicate that de novo synthesis of (pro)insulin occurs also during culture of fetal rat pancreas explanted relatively late in gestation.

High-frequency ultrasonic attenuation in superfluid helium under pressure.

Abstract: We attribute the formation of a shoulder in the high-frequency ultrasonic attenuation in superfluid helium under pressure to a restriction on the three-phonon process with thermal phonons. The restriction is proposed to follow from the pressure dependence of the phonon dispersion at zero temperature. The steep rise above the shoulder due to phonon-roton and roton-roton interactions also indicates large dispersion effects under pressure.

Physical and chemical characterization of pig kidney particulate aminopeptidase.

Abstract: Pig kidney particulate aminopeptidase (EC 3.4.1.2) was purified by a modification of the procedure of Wachsmuth et al. [3] to a state of homogeneity according to criteria of ultracentrifugation and polyacrylamide gel electrophoresis, and some of its physical and chemical properties were determined. The purified enzyme (specific activity 30 ± 3 μmoles leucine-p-nitroanilide hydrolyzed/min/mg) has a s20,w = 9.82 S at pH 8 and a molecular weight of about 280,000 as determined by high speed sedimentation equilibrium. Divergence between the number-, weight- and z- average molecular weights, and a sharp decrease of these values at low protein concentration, suggest that one is dealing with an associating-dissociating system. Amino acid analysis revealed the presence of considerable quantities of carbohydrates in the enzyme. Colorimetric, gas chromatographic and enzymatic analyses demonstrated the presence of glucosamine, galactose, mannose, fucose and sialic acid residues in the ratio of 1:0.89:0.75: 0.13: 0.13, amounting to ca. 400 residues or 20% (56,000 daltons) of the molecular weight. With the exception of sialic acid, the carbohydrate content was remarkably constant from preparation to preparation. Analyses by both atomic absorption spectrometry and the dithizone method showed that zinc–the only metal found in significant amount–was always present in the ratio of 2 atoms per molecule. It is therefore proposed that pig kidney particulate aminopeptidase is a Zn-containing glycoportein.

The limiting absorption principle and spectral theory for steady-state wave propagation in inhomogeneous anisotropic media

Abstract: Many wave propagation phenomena of classical physics are governed by systems of the Schrodinger form-iD t u+Λu=f(x,t) where 1 $$\Lambda = - iE(x)^{ - 1} \sum\limits_{j = 1}^n {(A_j D_j )} $$ , (1) E(x) and the A j are Hermitian matrices, E(x) is positive definite and the Aj are constants. If f(x, t)=e −iλt f(x) then a corresponding steady-state solution has the form u(x, t)=e−i λ tν(x) where ν(x) satisfies (Λ-λ) ν=f(x), xeR n . (2) This equation does not have a unique solution for λeR 1−{0} and it is necessary to add a radiation condition for ¦ x ¦ → ∞ which ensures that ν(X) behaves like an outgoing wave. The limiting absorption principle provides one way to construct the correct outgoing solution of (2). It is based on the fact that Λ defines a self-adjoint operator on the Hilbert space ℋ defined by the energy inner product 2 $$(u,v) = \int\limits_{R^n } {u^* } E{\text{ }}v{\text{ }}d{\text{ }}x$$ . It follows that if ζ=λ+iσ and σ≠0 then (Λ-ζ) ν=f has a unique solution 3 $$v(,\zeta ) = R_\zeta (\Lambda )f \in $$ ℋ where 4 $$R_\zeta (\Lambda ) = (\Lambda - \zeta )^{ - 1} $$ is the resolvent for Λ on ℋ. The limiting absorption principle states that 5 $$v(,\lambda ) = \mathop {\lim }\limits_{\sigma \to 0} v(,\lambda + i\sigma )$$ (3) exists, locally on R n, and defines the outgoing solution of (2). This paper presents a proof of the limiting absorption principle, under suitable hypotheses on E(x) and the A j . The proof is based on a uniqueness theorem for the steady-state problem and a coerciveness theorem for nonelliptic operators Λ of the form (1) which were recently proved by the authors. The coerciveness theorem and limiting absorption principle also provide information about the spectrum of Λ. It is proved in this paper that the point spectrum of Λ is discrete (that is, there are finitely many eigenvalues in any interval) and that the continuous spectrum of Λ is absolutely continuous.

On the role of cyclic amp in insulin release: i. overall effects in cultured fetal rat pancreas*

Abstract: The whole of this monograph serves to emphasize that, ever since 3', 5' cyclic AMP was discovered by Sutherland and his co-workers, there has been increasing recognition of the key role played by this nucleotide in living systems through a number of metabolic actions (for reviews, see this monograph and References 1-4). Thus, cyclic AMP is not only an obligatory messenger during the action of many hormones, but also a repeatedly recognized mediator during their secretion. In the specific case of insulin, cyclic AMP or some of its derivatives, or agents known to favor its accumulation within cells, were early shown to stimulate insulin secretion in vivo and in vitro.6-s In this report, we shall briefly review the effects in vitro of cyclic AMP and of phosphodiesterase inhibitors on insulin release from a preparation of cultured fetal rat pancreas. As previously shown,g-ll this preparation is advantageous in that the culture conditions permit a prolonged period of stabilization of the fetal explants, while maintaining excellent cellular preservation. Further, when cultured in the presence of relatively high concentrations of glucose, the ratio of endocrine to exocrine tissue may reach values as high as 0.2-0.3 (by comparison with a ratio of 0.02 in the adult pancreas) and the endocrine tissue has been found to consist principally of well-granulated B cells actively synthesizing and storing insulin. The preparation hitherto seemed disadvantageous in that it did not permit scrutiny of insulin release dynamics and it also seemed to represent a specialized functional state still retaining major fetal characteristics. Dynamic insulin release studies have now become possible, however, and the preparation may well be particularly favorable in that it may allow for the as yet indirect characterization of a cyclic AMP effect on the maturation of fetal insulin release mechanisms.