Showing papers by "Université libre de Bruxelles published in 1992"

An incomplete contracts approach to financial contracting

Abstract: We analyze incomplete long-term financial contracts between an entrepreneur with no initial wealth and a wealthy investor. Both agents have potentially conflicting objectives since the entrepreneur cares about both pecuniary and non-pecuniary returns from the project while the investor is only concerned about monetary returns. We address the questions of (i) whether and how the initial contract can be structured in such a way as to bring about a perfect coincidence of objectives between both agents (ii) when the initial contract cannot achieve this coincidence of objectives how should control rights be allocated to achieve efficiency? One of the main results of our analysis concerns the optimality properties of the (contingent) control allocation induced by standard debt financing.

The complete DNA sequence of yeast chromosome III.

Abstract: The entire DNA sequence of chromosome III of the yeast Saccharomyces cerevisiae has been determined. This is the first complete sequence analysis of an entire chromosome from any organism. The 315-kilobase sequence reveals 182 open reading frames for proteins longer than 100 amino acids, of which 37 correspond to known genes and 29 more show some similarity to sequences in databases. Of 55 new open reading frames analysed by gene disruption, three are essential genes; of 42 non-essential genes that were tested, 14 show some discernible effect on phenotype and the remaining 28 have no overt function.

High-dose recombinant tumor necrosis factor alpha in combination with interferon gamma and melphalan in isolation perfusion of the limbs for melanoma and sarcoma

Abstract: PURPOSETo determine the toxicity and the therapeutic efficacy of the combination of the recombinant tumor necrosis factor alpha (rTNF alpha), recombinant interferon gamma (rIFN-gamma), and melphalan, we designed a protocol using isolation limb perfusion (ILP) with hyperthermia for in-transit metastases of melanoma and recurrent sarcoma. The triple combination was chosen because of the reported synergistic antitumor effect of rTNF alpha with IFN-gamma and of rTNF alpha with alkylating agents.PATIENTS AND METHODSTwenty-three patients received a total of 25 ILPs with the triple combination. There were 19 females and four males with either multiple progressive in-transit melanoma metastases of the extremities (stage IIIa or IIIab; 19 patients) or recurrent soft tissue sarcoma (five). The rTNF alpha was injected as a bolus in the arterial line, and total dose ranged between 2 and 4 mg, under hyperthermic conditions (40 degrees C to 40.5 degrees C) for 90 minutes. The rIFN-gamma was given subcutaneously (SC) on...

The thyrotropin receptor and the regulation of thyrocyte function and growth.

Abstract: I. Introduction IN classical physiology, the main regulation of the thyroid gland involves a positive control by pituitary TSH. The pituitary thyrotrophs that synthesize and secrete TSH are submitted to tonic stimulation by the hypothalamic TRH and to negative feedback by T3, which is generated in these cells from plasma T4 (1, 2). The predominant role of TSH in thyroid regulation is exemplified by physiological experiments and pathological situations. Hypophysectomy, or treatment with thyroid hormones that reduces plasma TSH levels without interfering with other pituitary functions, almost abolishes thyroid function and greatly reduces the weight and cell mass of the gland. Conversely, chronic inhibition of the synthesis of thyroid hormones, and thus of their secretion, which greatly enhances TSH plasma levels, enhances thyroid growth and iodine metabolism upstream from the inhibited step. In pathology, hyperthyrotropinemia caused by pituitary adenomas induces hyperthyroidism and goiter. Hypopituitarism ...

Physiological and pathological regulation of thyroid cell proliferation and differentiation by thyrotropin and other factors

Abstract: I. Cell Proliferation in Normal Thyroid Tissue In Vivo ............................................... A. Physiological situation ........................................................................... B. Growth under stimulatory conditions ........................................................... C. Coordination between various thyroid cell types ................................................ D. Stem cells ........................................................................................ II. Methodology and Model Systems for Study of Thyroid Growth ................................... A. Model systems ................................................................................... B. Methodology: indexes of cell proliferation ...................................................... C. Working definition: growth control ratio ........................................................ III. Differentiation, Determination, Differentiation Expression ....................................... A. Thyroid system .................................................................................. B. Model for thyroid ................................................................................ IV. Extracellular Signals Involved in Control of Proliferation of Thyroid Cells ....................... A. Thyrotropin ...................................................................................... B. Iodine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Other hormones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Pathological signals .............................................................................. E. Local signals ..................................................................................... V. Pathways Regulating Thyroid Cell Proliferation ................................................... A. General considerations .......................................................................... B. Mitogenic and differentiating action of thyrotropin ............................................ C. Effect of factors other than thyrotropin on proliferation and differentiation ................. D. Role of adenosine 3’,5’-cyclic monophosphate, phosphatidylinositol bisphosphate, and tyrosine protein kinase cascades in thyrocyte proliferation ......................................... E. Kinetics of biochemical events in various thyroid mitogenic pathways ........................ F. Role of autocrine loop ............................................................................ VI. Apparently Opposite Programs: Proliferation and Differentiation Expression Are Induced by Thyrotropin and Adenosine 3’,5’-Cyclic Monophosphate Cascade .............................. VII. Growth Control and Goitrogenesis .................................................................. A. General concepts ................................................................................. B. Graves’ disease ................................................................................... C. Congenital defects ............................................................................... D. Thyroid adenoma ................................................................................ E. Sporadic goiter ................................................................................... VIII. Hypothetical and Existing Examples of Constitutive Activation of Adenosine 3’,5’-Cyclic Monophosphate Cascade ........................................................................ A. Adenylate cyclase-coupled receptors ............................................................ B. Cyclase-activating guanosine triphosphate-binding protein .................................... C. Adenosine 3’,5’-cyclic monophosphate-dependent protein kinase ............................... D. Negative controls of adenosine 3’,5’-cyclic monophosphate cascade ............................. IX. Conclusions .......................................................................................... 667 667 668 668 669 669 669 670 671 671 671 672 673 673 674 674 674 674 675 675 676 677

Expression of members of the putative olfactory receptor gene family in mammalian germ cells

Abstract: A series of genomic and complementary DNA clones encoding new putative members of G protein-coupled receptors were isolated using homology cloning and low-stringency polymerase chain reaction. Among the unidentified receptors ('orphan receptors'), a human genomic clone (HGMP07) was characterized by the presence of its transcripts in the testis and by its belonging to a large subfamily of genes sharing extensive sequence similarities. Sequence comparison demonstrated that this gene subfamily is the human counterpart of the putative rat olfactory receptors cloned recently. Another 48 members of the family were cloned. Northern blotting further demonstrated the presence of olfactory receptor transcripts in germ cells. Our finding suggests that a common receptor gene family encodes olfactory receptors and sperm cell receptors that could be involved in chemotaxis during fertilization.

Mapping of a gene predisposing to early-onset Alzheimer's disease to chromosome 14q24.3

Abstract: Genetic linkage studies with chromosome 21 DNA markers and mutation analysis of the beta-amyloid protein precursor gene located in 21q21.3 have indicated that early-onset Alzheimer's disease (EOAD) is a heterogeneous disorder for which at least one other chromosomal locus exists. We examined two extended histopathologically confirmed EOAD pedigrees, AD/A and AD/B, with highly informative short tandem repeat (STR) polymorphisms and found complete linkage of the disease to a (CA)n dinucleotide repeat polymorphism at locus D14S43 in 14q24.3 (Zmax = 13.25 at theta = 0.0). Using additional chromosome 14 STR polymorphisms we were able to delineate the region containing the EOAD gene to an area of, at most, 8.9 centiMorgans between D14S42 and D14S53, flanking D14S43 on both sides.

The virtues of gradualism and legitimacy in the transition to a market economy

Abstract: This paper presents a simplified model of sectoral restructuring in Eastern Europe A move towards allocative efficiency is desired by the reform-minded government, but the shift to higher productivity which such efficiency requires would lead to massive layoffs and labour reallocation in the transition period We look at the impact of political constraints (unanimity and/or majority worker approval) on reform proposals when the government faces a heterogeneous workforce, holding private information on relative outside opportunities When the budgetary consequences of exit compensations are so important as to make partial reforms preferable to full reforms, gradualism emerges as the optimum in a dynamic context without government commitment It is also shown that under democratic majority rule, a government in control of the agenda of reforms can win majority approval for plans which end up hurting majority interests intertemporally by threatening to switch majorities in future reform proposals(This abstract was borrowed from another version of this item)

Economic Reform and Dynamic Political Constraints

Abstract: In this paper, we examine the impact of political constraints on economic reform plans, with special reference to the transition from centrally planned to market economies. We analyse the problem of an agenda-setting reform-minded Government facing a bureaucracy or industrial sector for which allocative efficiency requires redundancies and an increase in work intensity. The Government also tries to minimize the rents conceded to its heterogeneous workforce. We examine two types of political constraints: unanimity rule and majority rule, both in a one-period and a two-period horizon. The main results are the following. First of all, we show how adverse selection and time-consistency may generate the widely-observed feature of gradualism as an ingredient of an optimal reform. Second, under a majority rule, it is shown to be possible for the Government to obtain a majority vote for a reform scheme that intertemporally hurts majority interests. Indeed, the Government can improve rent extraction through the strategic use of the threat of future proposals: the group which expects to be in the minority tomorrow may accept concessions, while its votes can be used to extract rents from another group. These results suggest that, in a dynamic context, democratic constraints should not be overestimated as an obstacle against efficiency-enhancing economic reforms. The results of this paper may throw some light on the political economy of current reforms in Eastern Europe. Governments, and political decision-makers in general, always face political constraints when elaborating reform proposals. They know that the need to overcome potential opposition from various groups of the population constrains proposals for change. Political constraints vary, depending on the specific institutional structure of society, and are clearly different under a military dictatorship than under a parliamentary democracy. The role of political constraints seems particularly important in Eastern Europe today, where new democratic governments face the huge task of achieving the transition to a market economy. While the introduction of democracy may have removed some important obstacles to economic change (namely, the veto-power of a powerful nomenclatura under communist one-party rule), fears are expressed that it could potentially jeopardize economic reforms which may, during the transition period, hurt a majority of the population.' What can economic theory tell us about optimal economic reform under political constraints? This paper starts addressing this ambitious question by looking at structural reform, focusing on a restructuring of economic sectors which requires massive redundancies and a significant rise in labour productivity. Our model illustrates the case of planning

Structural requirements for the occupancy of pituitary adenylate-cyclase-activating-peptide (PACAP) receptors and adenylate cyclase activation in human neuroblastoma NB-OK-1 cell membranes. Discovery of PACAP(6-38) as a potent antagonist.

Abstract: In these structure activity studies, the 46 analogs of the 27-amino-acid form of the pituitary-adenylate-cyclase-activating peptide, PACAP(1-27), and the 38-amino-acid form, PACAP(1-38), were either monosubstituted or bisubstituted at positions 1-3, 20 and 21 or N-terminally shortened. All analogs were compared on human neuroblastoma NB-OK-1 cell membranes for their ability to occupy 125I-[AcHis1]PACAP(1-27)-labelled receptors (AcHis, N alpha-acetylhistidine) and to activate adenylate cyclase (in terms of potency and intrinsic activity). The monophasic slope of dose/effect curves on both parameters suggested interaction with one class of PACAP receptor. Residues 28-38 in the C-terminally extended peptide, PACAP(1-38), played a favorable role in recognition, in that receptors coupled to adenylate cyclase were, in general, more sensitive to PACAP(1-38) analogs than to the corresponding PACAP(1-27) analogs. At variance with PACAP(6-27), PACAP(6-38) was well recognized and acted as a potent competitive antagonist (Ki 1.5 nM). Residues 1-3 were all important in enzyme activation: modification of the beta-turn potential gave full agonists (the LAla2 and DAla2 derivatives) or partial agonists (LPhe2 and DPhe2; LArg2 and DArg2; Glu3 and Asn3). Finally, a proper alpha-helix was also important: the combined substitution of Lys21/Lys22 by Gly21/Gly22 decreased the binding affinity sharply.

Antigen-pulsed dendritic cells can efficiently induce an antibody response in vivo.

Abstract: The aim of this study was to develop an immunization procedure avoiding external adjuvant. Data are presented showing that syngeneic dendritic cells (DC), which have been pulsed in vitro with antigen, induce a strong antibody response in mice. By contrast, antigen (Ag)-pulsed low-density B cells, although equally able to induce interleukin 2 secretion by an Ag-specific T cell hybridoma in vitro, only weakly prime the mice in vivo. Moreover, we show that the injection of Ag-pulsed DC induces the synthesis of isotypes similar to the immunoglobulin classes detected after immunization with the same Ag in complete Freund's adjuvant. Importantly, high amounts of IgG2a antibodies are produced, suggesting that T helper type 1 cells are activated. Collectively, these data indicate that DC can initiate a primary humoral response and that they may be used as physiological adjuvant in vivo.

Epidemiologic typing and delineation of genetic relatedness of methicillin-resistant Staphylococcus aureus by macrorestriction analysis of genomic DNA by using pulsed-field gel electrophoresis.

Abstract: To evaluate the usefulness of phenotypic and genotypic analyses for the epidemiologic typing of methicillin-resistant Staphylococcus aureus (MRSA), we characterized 64 epidemic MRSA isolates and 10 sporadic methicillin-susceptible S. aureus isolates from a university hospital and 18 MRSA isolates from hospitals in different geographical areas. Chromosomal DNA macrorestriction analysis with SstII was resolved by pulsed-field gel electrophoresis and compared with antibiotype analysis, phage type analysis, and standard genomic DNA restriction analysis with BglII. Indices of the discriminatory ability of these methods were 0.982, 0.959, 0.947, and 0.959, respectively. Macrorestriction patterns of 94% of MRSA isolates from patients, personnel, and the environment associated with a nosocomial outbreak were closely related (similarity coefficient, 85 to 100%). In contrast, methicillin-susceptible S. aureus isolates showed a marked diversity of macrorestriction patterns (median similarity, 41%). MRSA isolates from other geographical areas showed diverse macrorestriction patterns, with the exception of four isolates displaying identical or closely related patterns; these isolates were associated with concurrent outbreaks in four other Belgian hospitals. A concordance of genomic DNA macrorestriction typing with phenotypic methods was observed for 60 to 65% of MRSA isolates, and a concordance with standard DNA restriction analysis was found for 79 to 98% of these isolates. In conclusion, genomic DNA macrorestriction analysis was a useful complement to phenotypic methods for delineating epidemic isolates of MRSA, for identifying their nosocomial reservoirs, and for tracing their intra- and interhospital spread. The genetic relatedness of MRSA isolates, as estimated by this technique, appeared to correlate with their space-time clustering.

A quantitative estimation of growth hormone secretion in normal man: reproducibility and relation to sleep and time of day.

Abstract: Recent reports, based on measurements of plasma GH levels, have challenged the concept that GH secretion is dependent on sleep and not modulated by circadian rythmicity. Because plasma levels reflect not only the secretory process, but also the effects of distribution and degradation, temporal limits of active secretion and, consequently, synchrony with other physiological events cannot be accurately estimated from circulating concentrations. The present study was undertaken to examine the roles of sleep and time of day in modulating pulsatile GH secretion, using a mathematical procedure (deconvolution) allowing secretory rates to be estimated from peripheral levels. Eight young nonobese healthy men participated each in six separate 16-h studies involving either normal or delayed sleep. Plasma GH levels were measured at 15-min intervals, and GH secretory rates were calculated by deconvolution. Each individual study was preceded by one night of habituation, and sleep was polygraphically recorded in all stu...

Fatal familial insomnia: Clinical and pathologic study of five new cases

Abstract: In 1986, we reported two anatomoclinical observations of a familial condition that we called "fatal familial insomnia" (FFI). We now present the pedigree as well as the clinical and neuropathologic findings in five new subjects. The pedigree includes 288 members from six generations. Men and women are affected in a pattern consistent with an autosomal dominant inheritance. The age of onset of the disease varies between 37 and 61 years; the course averages 13 months with a range of 7 to 25 months. Progressive insomnia (polygraphically proven in two cases); autonomic disturbances including hyperhidrosis, hyperthermia, tachycardia, and hypertension; and motor abnormalities including ataxia, myoclonus, and pyramidal dysfunction, were present in every case, but with variable severity and time of presentation. Sleep and autonomic disorders were the earliest signs in two subjects, motor abnormalities were dominant in one, and others had intermediate clinical patterns. Pathologically, all the cases had severe atrophy of the anterior ventral and mediodorsal thalamic nuclei. Other thalamic nuclei were less severely and inconsistently affected. In addition, most of the cases had gliosis of the cerebral cortex, a moderate degree of cerebellar atrophy with "torpedoes," and severe atrophy of the inferior olivary nuclei. One case also showed spongy degeneration of the cerebral cortex. We conclude that all the lesions were primary, and that FFI is a multisystem disease in which the different structures are primarily affected with different severity. The insomnia appears to correlate best with the major thalamic pathology. The possibility that FFI belongs to the group identified as prion diseases or diseases transmitted by unconventional agents is examined.

Neuromuscular electrical stimulation and voluntary exercise.

Abstract: Neuromuscular electrical stimulation (NMES) has been in practice since the eighteenth century for the treatment of paralysed patients and the prevention and/or restoration of muscle function after injuries, before patients are capable of voluntary exercise training. More recently NMES has been used as a modality of strengthening in healthy subjects and highly trained athletes, but it is not clear whether NMES is a substitute for, or a complement to, voluntary exercise training. Moreover the discussion of the mechanisms which underly the specific effects of NMES appears rather complex at least in part because of the disparity in training protocols, electrical stimulation regimens and testing procedures that are used in the various studies. It appears from this review of the literature that in physical therapy, NMES effectively retards muscle wasting during denervation or immobilisation and optimises recovery of muscle strength during rehabilitation. It is also effective in athletes with injured, painful limbs, since NMES contributes to a shortened rehabilitation time and aids a safe return to competition. In healthy muscles, NMES appears to be a complement to voluntary training because it specifically induces the activity of large motor units which are more difficult to activate during voluntary contraction. However, there is a consensus that the force increases induced by NMES are similar to, but not greater than, those induced by voluntary training. The rationale for the complementarity between NMES and voluntary exercise is that in voluntary contractions motor units are recruited in order, from smaller fatigue resistant (type I) units to larger quickly fatiguable (type II) units, whereas in NMES the sequence appears to be reversed. As a training modality NMES is, in nonextreme situations such as muscle denervation, not a substitute for, but a complement of, voluntary exercise of disused and healthy muscles.

Candidemia in immunocompromised patients.

Abstract: This study reviews data on patients with fungemia and confirms the high prevalence (50%) of infections caused by non-albicans species of Candida. Fungemia due to C. albicans or Torulopsis glabrata occurred significantly more often in patients with a solid tumor, while fungemia due to Candida tropicalis or Candida krusei was significantly more common in patients with hematologic malignancy (P = .001). For 31% of patients, only a single blood culture was positive for yeasts, and the prognosis for these patients was not significantly different than that for patients with three or more positive blood cultures (P = 1), including those who had C. albicans fungemia. The overall mortality rate was 41.8%, which is much lower than that previously reported in studies of patients with cancer. No significant difference was observed between patients treated with amphotericin B and those treated with fluconazole in this retrospective analysis. Although no significant difference was observed in the mortality rate among patients who had fungemia with or without neutropenia, the incidence of disseminated candidiasis was significantly higher among neutropenic patients (P = .03).

The box calculus: a new causal algebra with multi-label communication

Abstract: A new Petri net calculus called the calculus of Petri Boxes is described. It has been designed to allow reasoning about the structure of a net and about the relationship between nets, and to facilitate the compositional semantic translation of high level constructs such as blocks, variables and atomic actions into elementary Petri nets. The calculus is located ‘midway’ in such a translation.

Trail laying behaviour during food recruitment in the ant Lasius niger (L.)

Abstract: Summary The trail-laying behaviour of foragers of the ant Lasius niger was observed in the laboratory on a 20 cm bridge between the nest and the food source. We measured both the frequency of trail laying, as defined by the proportion of trips during which trail laying occurred, and its intensity, as defined by the number of marks laid during one bridge crossing. Foragers do not exhibit trail-laying behaviour until a food source is discovered. Trail laying then occurs more or less equally both to and from the nest, and both its frequency and intensity decrease as the recruitment proceeds. Foragers from very small colonies less than a year old appear to have quantitatively the same trail laying behaviour as those from older and much larger colonies. Groups of recruiters and recruits were individually marked. Their trail laying intensity was similar, both for trips to and from the nest, and for an ant's first, second, third and fourth trip. The frequency diminished rapidly with the number of trips made by each individual, and was 2-3 times higher for recruiters than for recruits, for trips both to and from the nest. Even though foragers stop marking after a variable number of passages, they continue to move between the nest and the food source, and other ants start marking. Different foragers appear to have widely different levels of trail laying, although we cannot say whether these differences are stable between different recruitments. Trail laying is strongly affected by the foragers' position on the bridge, especially for ants returning to the nest which lay up to five times more on the segment closest to the source than that closest to the nest. Foragers on a weakly marked trail appear to mark more than those on a wellmarked trail. However, this effect is weak and could partly be attributed to their lower speed. Finally, a model using the experimental data gathered on the individuals' trail-laying behaviour reproduced satisfactorily the colony's overall trail laying.

A *-product on SL(2) and the corresponding nonstandard $$(\mathfrak{s}\mathfrak{l}({\text{2}}))$$

Abstract: We obtain Zakrzewski's deformation of Fun SL(2) through the construction of a *-product on SL(2). We then give the deformation of $$(\mathfrak{s}\mathfrak{l}({\text{2}}))$$ dual to this, as well as a Poincare basis for both algebras.

Structure and orientation of the surfactant-associated protein C in a lipid bilayer.

Abstract: The secondary structure of native and depalmitoylated porcine surfactant-associated protein C (SP-C) was studied by attenuated total reflection Fourier-transform infrared spectroscopy. Both forms of porcine SP-C adopt mainly an alpha-helical conformation. These two forms of the protein were reconstituted in a lipid bilayer. The insertion of the protein in a membrane is associated with an increase of the alpha-helical content. Dichroic measurements show that, in both cases, the long axis of the alpha-helix is oriented parallel to the lipid acyl chains.

A gene from the variant surface glycoprotein expression site encodes one of several transmembrane adenylate cyclases located on the flagellum of Trypanosoma brucei.

Abstract: The bloodstream form of Trypanosoma brucei contains transcripts of at least four genes showing partial sequence homology to the genes for eucaryotic adenylate and guanylate cyclases (S. Alexandre, P. Paindavoine, P. Tebabi, A. Pays, S. Halleux, M. Steinert, and E. Pays, Mol. Biochem. Parasitol. 43:279-288, 1990). One of these genes, termed ESAG 4, belongs to the polycistronic transcription unit of the variant surface glycoprotein (VSG) gene. Whereas ESAG 4 is transcribed only in the bloodstream form of the parasite, the three other genes, GRESAG 4.1, 4.2, and 4.3, are also expressed in procyclic (insect) forms. These genes differ primarily in a region presumed to encode a large extracellular domain. We show here that ESAG 4-related glycoproteins of about 150 kDa can be found in the trypanosome membrane, that they are detected, by light and electron gold immunocytochemistry, only at the surface of the flagellum, and that the products of at least two of these genes, ESAG 4 and GRESAG 4.1, can complement a Saccharomyces cerevisiae mutant for adenylate cyclase. The recombinant cyclases are associated with the yeast membrane fraction and differ with respect to their activation by calcium: while the GRESAG 4.1 and yeast cyclases are inhibited by calcium, the ESAG 4 cyclase is stimulated. ESAG 4 thus most probably encodes the calcium-activated cyclase that has been found to be expressed only in the bloodstream form of T. brucei (S. Rolin, S. Halleux, J. Van Sande, J. E. Dumont, E. Pays, and M. Steinert. Exp. Parasitol. 71:350-352, 1990). Our data suggest that the trypanosome cyclases are not properly regulated in yeast cells.

Thyroid expression of an A2 adenosine receptor transgene induces thyroid hyperplasia and hyperthyroidism.

Abstract: Cyclic AMP (cAMP) is the major intracellular second messenger of thyrotropin (TSH) action on thyroid cells. It stimulates growth as well as the function and differentiation of cultured thyrocytes. The adenosine A2 receptor, which activates adenylyl cyclase via coupling to the stimulating G protein (Gs), has been shown to promote constitutive activation of the cAMP cascade when transfected into various cell types. In order to test whether the A2 receptor was able to function similarly in vivo and to investigate the possible consequences of permanent adenylyl cyclase activation in thyroid cells, lines of transgenic mice were generated expressing the canine A2 adenosine receptor under control of the bovine thyroglobulin gene promoter. Thyroid-specific expression of the A2 adenosine receptor transgene promoted gland hyperplasia and severe hyperthyroidism causing premature death of the animals. The resulting goitre represents a model of hyperfunctioning adenomas: it demonstrates that constitutive activation of the cAMP cascade in such differentiated epithelial cells is sufficient to stimulate autonomous and uncontrolled function and growth.

Electron conducting organic coating of mild steel by electropolymerization

Abstract: The aim was to coat mild steel with an electron conducting polymer in order to replace any possible electrochemical corrosion of the metal by another electrochemical reaction occurring on top of the film. In view of potential industrialization, electropolymerization of a water soluble monomer was studied. In most cases, this was achieved by oxidation, and the substrate had to be passivated. Polyaniline, was obtained in nitric acid solution. Films had a good structure but were brittle and powdery on the surface. Except on tin free steel, they were insulating. Polypyrrole was a better candidate. Prepared from a Na2SO4 solution, films were conductive, ensured good corrosion resistance of the substrate but they were brittle and adhesion to the substrate was not high. Furance, thiophene and iron substituted vinylpyridine complex were tried without success. Further, research should consider copolymerization of pyrrole with other monomers.

Probabilistic Reactor Dynamics —I: The Theory of Continuous Event Trees

Abstract: The concept of probabilistic reactor dynamics is formalized in which deterministic reactor dynamics is supplemented by the fact that deterministic trajectories in phase-space switch to other trajec...