Showing papers by "University of Geneva published in 1979"
TL;DR: Three-dimensional reconstructions of islets of Langerhans reveal a marked difference in the number of cells containing glucagon and pancreatic polypeptide depending on the anatomical location of the islet in the pancreas, contradicting the assumption that all islets in the Pancreas are similar in their endocrine cell content.
Abstract: Three-dimensional reconstructions of islets of Langerhans, based on immunofluorescent staining of successive serial sections with antiserums to insulin, glucagon, somatostatin, and pancreatic polypeptide reveal a marked difference in the number of cells containing glucagon and pancreatic polypeptide depending on the anatomical location of the islet in the pancreas. The two types of islets are situated in regions of exocrine tissue that are drained by different excretory ducts. This demonstration contradicts the assumption that all islets in the pancreas are similar in their endocrine cell content.
253 citations
TL;DR: A combination of pulse- chase biosynthetic labeling protocols, subcellular fractionation, and electron microscope autoradiography was used in conjunction with inhibitors of glycosylation and agents which block Ig exit from the rough endoplasmic reticulum (RER) or Golgi cisternae.
Abstract: Immunoglobulin M (IgM)-secreting murine plasmablasts have been used to explore the cytologic site(s) of the successive modifications of the polypeptide H and L chains (steps of glycosylation, chain assembly, and polymerization) which occur during intracellular transport (ICT) and the interrelationships between these events. A combination of pulse-chase biosynthetic labeling protocols (using amino acids and sugars), subcellular fractionation, and electron microscope autoradiography was used in conjunction with inhibitors of glycosylation and agents (carboxyl cyanide m-chlorophenyl hydrazone [CCCP] and monensin) which block Ig exit from the rough endoplasmic reticulum (RER) or Golgi cisternae. The data are consistent with the following conclusions: (1) Sugar addition and modification occur in three main steps: (a) en bloc addition of core sugars to nascent H chains, (b) partial trimming of these oligosaccharide chains in the RER, (c) quasiconcerted addition of terminal sugars (galactose, fucose, and sialic acid) in a very distal compartment between monensin-sensitive Golgi cisternae and the cell surface. (2) H and L chain assembly occurs between nascent H chains and a pool of free light chains present in the RER, followed by interchain disulfide bonding and rapid assembly of monomers into J chain-containing pentamers in the RER. Small amounts of various apparently non-obligatory intermediates in polymerization are also formed. (3) Carbohydrate addition is not required for chain assembly, polymerization, and secretion since completely unglycosylated chains (synthesized in the presence of deoxyglucose or tunicamycin) undergo polymerization and are secreted (although at a reduced rate). (4) Surface 8s IgM molecules do not represent a step in the IgM secretory pathway.
222 citations
TL;DR: Systematic sampling of human necropsy pancreases has revealed that pancreatic polypeptide cells are not distributed equally in the gland, and PP-cells are the most abundant cell type in the posterior part of the Pancreas as a discrete lobe.
Abstract: Systematic sampling of human necropsy pancreases has revealed that pancreatic polypeptide (PP) cells are not distributed equally in the gland. PP-cells are the most abundant cell type in the posterior part of the pancreatic head while they are scarce or absent in the remainder of the gland. The PP-rich part of the head can be separated by blunt dissection from the pancreas as a discrete lobe. This lobe probably originates from the ventral pancreatic bud during embryogenesis. A quantitative study of the immunofluorescent endocrine cell types (insulin, glucagon, somatostatin and pancreatic polypeptide cells) in PP-rich and PP-poor regions of pancreases in 8 subjects with ages ranging from 33 fetal weeks to 80 years, showed that the proportions of the cell types were different in youngs and adults.
150 citations
TL;DR: The decreased brain weight and volume coupled with the observed morphometric changes in individual neuronal soma size suggest that the ob/ob mouse brain differs considerably from that of controls.
145 citations
143 citations
01 Jan 1979
130 citations
TL;DR: More than 300 altered lac repressor proteins are generated, by employing nonsense mutations at 90 positions in the lacI gene together with eight different nonsense suppressors, which allows the substitution of lysine, serine, tyrosine, leucine and glutamine at virtually all of the respective locations in the repressor.
127 citations
TL;DR: In this paper, the authors give necessary and sufficient conditions in terms of the generators for the inequality of a positivity preserving semigroup to hold pointwise, where A is the generator of a semigroup and B is a self-adjoint operator.
123 citations
TL;DR: The significance of the lowest-order QCD prediction for the annihilations of heavy quark-antiquark bound states is analyzed in this article, where a bad convergence of the relative perturbative expansion is found, demanding for its safe application a value of relevant momentum definitely higher than that of charmonium physics.
120 citations
TL;DR: In this paper, the deuterium atoms occupy tetrahedral interstices formed by two Zr and two Mn atoms and represent a 3-dimensional infinite network of diffusion paths for the D atoms.
117 citations
TL;DR: The results reported here suggest that actin is involved in the condensation of Xenopus chromosomes.
Abstract: The role of contractile proteins in the structural organisation of the interphase nucleus and of metaphase chromosomes is largely unknown. Actin has been found in interphase nuclei of different species, especially in association with condensed chromatin. In the germinal vesicle (nucleus) of Xenopus oocytes, actin has been localised in the nuclear gel supporting the chromosomes and the extrachromosomal nucleoli. It has been reported that the premeiotic lampbrush chromosomes in these germinal vesicles are positively stained for actin and tubulin by the immunoperoxidase technique. Moreover, the longitudinal contraction of these chromosomes is ATP dependent. Therefore it has been suggested that actin participates in the structural organisation of the highly specialised lampbrush chromosomes. However, actin is not a major component of the metaphase chromosome scaffold. The results reported here suggest that actin is involved in the condensation of Xenopus chromosomes.
TL;DR: The results show that the two cloned Dm DNA segments derive from nonoverlapping regions of the Dm genome; that they contain homologous regions present once in 56H8 and twice in 132E3; and that each homologueous region is composed of three distinct contiguous sequence elements, x, y and z, which together define a 3 kb common unit.
TL;DR: A study of the organization of the two loci is completed, using deficiencies that delete one or other locus, and the number of the hsp 70 genes at each locus is estimated, finding that in at least three strains of files there are a total of five coding sequences.
TL;DR: SDS-polyacrylamide gel electrophoresis of the digestion products of native collagen mixed with concentrated gingival washings showed that the collagenase in theGingival crevice is partly of mammalian origin.
TL;DR: Intra-individual variations are seen at different times of the year at 2400 and 0800, with low values in spring and autumn and high values in summer and winter.
Abstract: Immunoreactive melatonin has been studied in normal human volunteers, both men and women, at different times of day and different times of the year. At 2400, but not at 0800 or 1200, there are very large inter-individual variations in mean levels, the maximum difference being fivefold. Intra-individual variations are seen at different times of the year at 2400 and 0800, with low values in spring and autumn and high values in summer and winter.
TL;DR: It is reported here that the sequences complementary to the 70,000 dalton protein mRNA appear to be confined to a major portion of the largest element of the common unit and that the other sequence elements are located at the 5' end of the gene.
TL;DR: In this paper, the absorption of subcutaneously injected insulin was examined by injecting semisynthetic [3H] insulin in anaesthetized pigs and subsequently analysing the tissue excised from the injection site.
Abstract: The absorption of subcutaneously injected insulin was examined by injecting semisynthetic [3H] insulin in anaesthetized pigs and subsequently analysing the tissue excised from the injection site. Contrary to previously accepted views, a significant proportion of insulin was degraded at the injection site. The disappearance of intact [3H] insulin from the injection site followed a monoexponential function with a half-time of 59 min.
TL;DR: A detailed qualitative investigation of the behavior of lead complexes with fulvic substances has been carried out using several polarographic techniques, e.g. d.c. polarography, normal and differential pulse polarography and cyclic voltammetry.
TL;DR: Mu insertion seems to have a striking similarity to typical IS-mediated insertions that were found to be associated with a short DNA duplication at the target site.
TL;DR: The decrease in resting oxygen consumption induced by starvation was found to occur not only in euthyroid rats but also in hypothyroid and even in Hypothyroid animals treated with triiodothyronine.
Abstract: The decrease in resting oxygen consumption induced by starvation was found to occur not only in euthyroid rats but also in hypothyroid and even in hypothyroid animals treated with triiodothyronine. Furthermore, the effectiveness of triiodothyronine was decreased when given to hypothyroid animals.
TL;DR: These analyses reveal regions of the protein involved in different repressor functions, and the pattern of mutational sites in the lacI gene leading to loss of inducer binding of the repressor is striking.
TL;DR: Plasma and serum of humans or experimental animals contain a factor which destabilizes F-actin, and after incubation with F- actin does not modify the position of the actin band on a SDS polyacrylamide gel, Hence it probably depolymerizes F -actin.
Abstract: Plasma and serum of humans or experimental animals contain a factor which destabilizes F-actin. The factor has no DNAse or thrombin activity and after incubation with F-actin does not modify the position of the actin band on a SDS polyacrylamide gel. Hence it probably depolymerizes F-actin.
TL;DR: To say that a given phoneme is not sufficiently defined in articulatory or acoustic terms but needs to be fitted into the total system of sound relations peculiar to the language is, at bottom, no more mystenous than tosay that a club is not defined for us when it is said to be made of wood and to have such and such a shape.
Abstract: THE CONCEPT of the \"phoneme\" (a functionally significant unit in the rigi~IY.definedpattern or configuration of sounds peculiar to a language), as .dIs~mct from that of the \"sound\" or \"phonetic element\" as such (an objectIvely definable entity in the articu ated and perceived totality of speech), is be~oming more and more familiar to linguists. The difficulty that many stIll seem to feel in distinguishing between the two must event~ally disappear as the realization grows that no entity in human ex~enence.can be adequately defined as the mechanical sum or product of Its physIcal properties. These physical properties are needed of course to give us .the signal, as it were, for the identification of the given entity as a functIOnally significant point in a complex system of relatednesses; but for. any given context it is notorious how many of these physical propertIes are, or may be, overlooked as irrelevant, how one particular property, ,possessing for the moment or by social understanding an unusual sIgn value, may have a determinedness in the definition of the entity that is out of all proportion to its \"physical weight.\" As soon, h.owever, as we admit that all significant entities in experience are thus rev~sed from the physically given by passing through the filter of the functIOnally or relatedly meaningful, as soon as we see that we can never set up a scale of added or changed meanings that is simply c?ng~ent to the scale of physical increments, we implicitly make a distmctIOn, whether we know it or not, between the phoneme and the sound in that particular framework of experience which is known as language (actualized as speech). To say that a given phoneme is not sufficiently defined in articulatory or acoustic terms but needs to be fitted into the total system .of sound relations peculiar to the language is, at bottom, no more mystenous than to say that a club is not defined for us when it is said to be made of wood and to have such and such a shape a?d. such ,and such dimensions. We must understand why a roughly s~ilar ?bJect, not so different to the eye, is no club at all, and why a thIrd object, of very different color and much longer and heavier than the first, is for all that very much of a club. . Some linguists seem to feel that the phoneme is a useful enough concept In an abstract linguistic discussion-in the theoretical presentation of the f?rID of a language or in the comparison of related languages-but that It has small relevance for the actualities of speech. This point of
TL;DR: The gynogenetic offspring of the hybrid frogRana esculenta (R. ridibunda x R. lessonae) are exclusively of theridibunda type, due to the premeiotic exclusion of thelessonae genome from the hybrid's germ cells.
Abstract: The gynogenetic offspring of the hybrid frogRana esculenta (R. ridibunda x R. lessonae) are exclusively of theridibunda type. This is due to the premeiotic exclusion of thelessonae genome from the hybrid's germ cells.
TL;DR: The gene coding for the large subunit of ribulose 1,5-diphosphate carboxylase of Chlamydomonas reinhardii has been cloned and localized at a unique site on the physical map of the chloroplast genome to inhibit in vitro translation of LS when it is hybridized to poly(A) − RNA prior to translation.
TL;DR: The results reported here are considered together with the data from suppressed nonsense mutations, which are described in the preceding paper, to consider the possible significance with respect to repressor structure and function.
TL;DR: In this paper, the deuterium atoms are found to occupy two types of tetrahedral interstices in the metal atom host structure, which can be considered as forming a three-dimensional infinite network of diffusion paths.
TL;DR: The firing of a proportion of hypothalamic neurons in long-term cultures from the supraoptic nucleus was characterized by a phasic discharge pattern, and the activity of bursting pacemaker cells persisted during applications of Co2+ and was a function of membrane potential.
TL;DR: In this paper, a model for the electrode process corresponding to the reduction of Pb(II) complexed by fulvic substances is presented and a mathematical expression is given for the polarographic wave.
TL;DR: All of the chloroplast 23S ribosomal genes of C. reinhardii are interrupted by a 0.87 kb sequence, and the results show that the intervening sequence is flanked by two identical sets of 3 bp (5'-CGT) oriented as direct repeats.