Showing papers by "Université de Montréal published in 1990"

cDNA sequence of two distinct pituitary proteins homologous to Kex2 and furin gene products: tissue-specific mRNAs encoding candidates for pro-hormone processing proteinases.

Abstract: Based on the concept of sequence conservation around the active sites of serine proteinases, polymerase chain reaction applied to mRNA amplification allowed us to obtain a 260-bp probe which was used to screen a mouse pituitary cDNA library. The primers used derived from the cDNA sequence of active sites Ser* and Asn* of human furin. Two cDNA sequences were obtained from a number of positive clones. These code for two similar but distinct structures (mPCl and mPC2), each being homologous to yeast Kex2 and human furin. In situ hybridization (mPCl) and Northern blots (mPCl = 3.0 kb and mPC2 = 2.8 and 4.8 kb) demonstrated tissue and cellular specificity of expression, only within endocrine and neuroendocrine cells. These data suggest that mPCl and mPC2 represent prime candidates for tissue-specific pro-hormone converting proteinases.

Isospin analysis of CP asymmetries in B decays

Abstract: There is some theoretical uncertainty in the predictions for CP-violating hadronic asymmetries in neutral-B decays to CP eigenstates due to the existence of penguin diagrams. Using isospin relations, we show that it is possible to remove this uncertainty for the decays ${\mathit{B}}_{\mathit{d}}^{0}$\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}.

Parietal area 5 neuronal activity encodes movement kinematics, not movement dynamics.

Abstract: A previous study reported that proximal-arm related area 5 neurons showed continuously-graded changes in activity during unloaded arm movements in different directions (Kalaska et al. 1983), which resembled the responses of primary motor cortex cells in several respects (Georgopoulos et al. 1982). We report here that loading the arm reveals an important difference between cell activity in the two areas. Loads were continuously applied to the arm in different directions. The loads produced large continuously-graded changes in muscle activity but did not alter the handpath or joint angle changes of the arm during the movements. The activity of most area 5 cells was only weakly affected by the loads, and the overall pattern of population activity was virtually unaltered under all load conditions. This indicates that area 5 activity encodes the invariant spatial parameters (kinematics) of the movements. In contrast, many motor cortex cells showed large changes in activity during loading, and so signal the changing forces, torques or muscle activity (movement dynamics; Kalaska et al. 1989).

The Distribution of a Perpetuity, with Applications to Risk Theory and Pension Funding

Abstract: If Vk is the discount factor for the kth period, then Z = Σ k⩾1V 1...Vk Ck is the discounted value of a perpetuity paying Ck at time k. In some cases Z is also the limiting distribution of St =Vt (St-1 +Ct-1 ). This paper 1. reviews the literature concerning Z and {St } 2. considers continuous-time counterparts of Z and S, at the same time deriving the distribution of ∫ exp(-γt-σWt )1(0, ∞) (t)dt when W is Brownian motion; 3. gives applications to risk theory and pension funding.

Processing of local and global musical information by unilateral brain-damaged patients

Abstract: Melody processing in unilaterally brain-damaged patients was investigated by manipulating the availability of contour and metre for discrimination in melodies varying, respectively, on the pitch dimension and the temporal dimension. On the pitch dimension, right brain-damaged patients, in contrast to left braindamaged patients and normal controls, were found to be little affected by the availability of contour as a discrimination cue. However, both brain-damaged groups were impaired on tasks requiring consideration of pitch interval structure. These findings are consistent with hierarchical contribution of the cerebral hemispheres, with the right hemisphere being primary in representing the melody in terms of its global contour and the left hemisphere by filling in the intervallic structure. On the temporal dimension, only the discrimination of durational values (the rhythm) was found to be impaired by a lesion in either hemisphere, which spared, however, the metric interpretation of the musical sequences. These latter results are discussed in the light of current models of temporal processing. Finally, evidence of double dissociation between the processing of the pitch dimension and the processing of rhythm was obtained, providing further support for the need to fractionate musical perceptual abilities in order to arrive at a theory as to how the two hemispheres cohere to produce a musical interpretation of the auditory input.

Does proportional representation foster voter turnout

Abstract: . This paper examines the record of western democracies to measure the impact of differing electoral formulae on the rate of voter turnout. The record of 509 national elections in 20 countries provides the basis for a regression analysis that clearly identifies higher turnout rates in PR systems that cannot be explained by a wide variety of control variables or traditional arguments about PR. The data also reveal a marked increase in electoral turnout over the last century.

Job insecurity in managers: Antecedents and consequences

Abstract: To date, popular accounts and systematic studies of the effects of job insecurity have focused exclusively on firms in acute crisis. In contrast, this study examines perceptions of the reactions to insecurity as a chronic, ambiguous threat. None of the 1291 managers surveyed was currently facing layoff, but half worked for firms that had laid off managers in the previous five years and half worked in a stable, expanding firm. As in previous studies, concern about any aspect of job insecurity was associated with decreased personal well-being and deterioration of work behavior and attitudes. However, only a small minority of managers were seriously worried about imminent job loss, with substantially more anxious about a deterioration in working conditions and long-term security.

Advancing Knowledge about the Onset of Delinquency and Crime

Abstract: Our main concern is to advance knowledge about the onset of delinquency and crime. When a person commits an offense for the first time, it is only future experience that can establish with certainty whether that offense was the onset of a persistent and serious criminal career or whether it was simultaneously the person’s first and last offense. However, the age at which a first offense occurs is one of the best predictors (or even the best predictor; see Blumstein, Farrington, & Moitra, 1985) of the future course of the criminal career.

Common low-density lipoprotein receptor mutations in the French Canadian population.

Abstract: Familial hypercholesterolemia (FH) has a frequency of 0.2% in most populations of the world. In selected populations such as the Afrikaners in South Africa, the Christian Lebanese, and the French Canadians, the disease is more frequent due to the founder effect. Previous studies demonstrated that a single mutation at the LDL receptor locus, the so-called French Canadian deletion, makes up 60% of the mutant genes responsible for FH in the French Canadian population. In this study, efforts were directed to determine if there were other common LDL receptor mutations in this population. Three missense mutations were identified and each mutation was reproduced and expressed in vitro. Two of the three mutations result in the production of an LDL receptor protein that is not processed to its mature form at a normal rate. Molecular assays were developed to detect the mutations directly, and the LDL receptor genes of 130 French Canadian FH heterozygotes were screened for the presence of the three missense mutations as well as two deletions. LDL receptor mutations were detected in 76% of individuals and 14% had one of the three missense mutations.

Split delivery routing

Abstract: This article examines a relaxed version of the generic vehicle routing problem. In this version, a delivery to a demand point can be split between any number of vehicles. In spite of this relaxation the problem remains computationally hard. Since only small instances of the vehicle routing problem are known to be solved using exact methods, the vehicle route construction for this problem version is approached using heuristic rules. The main contribution of this article to the existing body of literature on vehicle routing issues in (a) is presenting a new vehicle routing problem amenable to practical applications, and (b) demonstrating the potential for cost savings over similar “traditional” vehicle routing when implementing the model and solutions presented here. The solution scheme allowing for split deliveries is compared with a solution in which no split deliveries are allowed. The comparison is conducted on six sets of 30 problems each for problems of size 75, 115, and 150 demand points (all together 540 problems). For very small demands (up to 10% of vehicle's capacity) no significant difference in solutions is evident for both solution schemes. For the other five problem sets for which point demand exceeds 10% of vehicle's capacity, very significant cost savings are realized when allowing split deliveries. The savings are significant both in the total distance and the number of vehicles required. The vehicles' routes constructed by our procedure tend to cover cohesive geographical zones and retain some properties of optimal solutions.

Fish Production Correlated with Primary Productivity, not the Morphoedaphic Index

Abstract: Estimates of the biological production of entire lake fish communities were collected from the published literature on lakes covering a wide range of geographic areas and trophic status Correlatio

Simple, rapid, and effective method of producing aortocaval shunts in the rat

Abstract: STUDY OBJECTIVE - The aim of the study was to develop a new procedure to produce abdominal aortocaval shunts in the rat without vascular microsurgery. PROCEDURE - The inferior vena cava and abdominal aorta were exposed by laparotomy. The aorta was punctured caudal to the left renal artery with an 18 gauge disposable needle which was advanced into the vessel, perforating the adjacent wall between aorta and vena cava and penetrating the latter. A bulldog vascular clamp was placed across the aorta cephalic to the puncture, the needle was withdrawn, and the aortic puncture point was sealed with a drop of cyanoacrylate glue. The clamp was removed 30 s later. Patency of the shunt was verified visually by swelling of the vena cava and admixture of arterial and venous blood. No local haemorrhages were seen. The laporatomy was then closed. The procedure takes less than 10 min. RESULTS - Of 11 rats which received this procedure, only one died within 24 h. All the other animals were killed 4 weeks after operation. Nine of these 10 animals had developed cardiac hypertrophy of about the same magnitude. There were no changes in sham operated controls. CONCLUSIONS - This is a reproducible, simple and rapid method of developing high output heart failure and cardiac hypertrophy in the rat which could be useful in many laboratories.

Mixed deoxyribo- and ribo-oligonucleotides with catalytic activity

Abstract: THE RNA of viroids and virusoids in plants, and the RNA tran-scripts of some tandemly repeated DNA sequences in the newt, can undergo self-catalysed cleavage to generate RNA with 5'′OH and 2′,3′-cyclic-phosphate termini1–4. These catalytic RNAs, or ribozymes, form a stem-loop secondary structure called a 'ham-merhead' in which the catalytic (ribozyme) and substrate sequences are brought close together (Fig. la). Catalytically active mimics of hammerhead ribozymes can be readily made using oligoribo-nucleotides5–7. Consequently, hammerhead analogues in which certain ribonucleotides are replaced by different ones have been constructed both to identify consensus residues required for cleavage activity and to determine the details of the cleavage mechanism8–10. But these ribonucleotide-replacements tend to alter the conformation of the hammerhead by changing hydrogen-bonding and stacking potential at the position of substitition. We have now constructed structurally less-disrupted hammerhead analogues in which deoxyribonucleotides, which lack 2′-OH groups, are substituted for ribonucleotides. These mixed RNA-DNA polymers11 were synthesized using a strategy for the chemical synthesis of RNA that is compatible with DNA synthesis12. Analy-sis of the cleavage products of several of these hammerhead analogues confirms the involvement in the reaction of the 2′-OH adjacent to the cleavage site in the substrate, and demonstrates that some 2′-OH groups in the catalytic region strongly affect activity. The results also indicate that the three-dimensional struc-ture producing nucleic acid-type catalysis is not restricted to RNA.

The case of the nonce loan in Tamil

Abstract: Nonce borrowings in the speech of bilinguals differ from established loanwords in that they are not necessarily recurrent, widespread, or recognized by host language monolinguals. With established loanwords, however, they share the characteristics of morphological and syntactic integration into the host language and consist of single content words or compounds. Furthermore, both types of loanwords differ fro m intrasentential code-switching —alternate sentence fragments in the two languages, each of which is grammatical by monolingual standards from the standpoints of appropriate function words, morphology, and syntax. In a large corpus of Tamil-English bilingual speech, many words of English origin are found in objects governed by Tamil verbs and vice versa. The equivalence constraint on intrasentential code-switching predicts that no code-switch should occur between verb and object in an SOV/SVO bilingual situation, and hence that objects whose language differs from that of the verb must be borrowed, if only for the nonce. To verify this prediction, we compare quantitatively the distribution across various syntactic contexts of both native Tamil and English-origin complements of Tamil verbs, and find them to be parallel. But the strongest evidence in favor of the nonce borrowing hypothesis comes from an analysis of variable accusative and dative case marking in these complements, in which the English-origin material is shown, morphologically and syntactically, to be virtually indistinguishable from Tamil (nonpronominal) nouns. In addition, we present supporting evidence from the genitive, locative, and other cases and from nonce borrowings from Tamil into these speakers' English.

Cold acclimation of wheat (Triticum aestivum): Properties of enzymes involved in proline metabolism

Abstract: Two cultivars of wheat (Triticum aestivum L.), a winter wheat, Kharkov, and a spring wheat, Glenlea, were acclimated under controlled conditions at 2 temperatures, 5°C and 25°C with a 12-h photoperiod. Water content, protein and proline concentrations were determined. Enzymatic properties (activity and apparent energy of activation) were investigated for enzymatic systems involved in 2 pathways of proline metabolism, the glutamic acid and ornithine pathways. Four enzymes were studied, proline dehydrogenase (PDH, EC 1.5.1.2), glutamate dehydrogenase (GDH, EC 1.4.1.2-4), glutamine synthetase (GS, EC 6.3.1.2) and ornithine transaminase (OT, EC 2.6.1.13). Cold acclimation led to an accumulation of proline, a decrease in water content and an increase in soluble protein, especially in winter wheat. For both cultivars, cold acclimation modulated enzyme properties of PDH and GDH. Increased activities of GS and OT were observed as a result of cold acclimation in both cultivars, with the greatest increase in Kharkov. The apparent energy of activation of these 2 enzymes decreased, particularly for Kharkov, which accumulated proline in cold conditions.

An update on Streptococcus suis identification.

Abstract: Streptococcus suis is a worldwide cause of a variety sular type 2 isolate was recovered in pure culture from of porcine infections. It has been isolated from cases lungs and kidneys of a 41⁄2-month-old aborted bovine of meningitis, bronchopneumonia, arthritis, pericarfetus and its placenta. This suggests that S. suis may ditis, endocarditis, polyserositis, septicemia, rhinitis, be pathogenic for more than 1 animal species. and abortion.20,22,24 Different alpha-hemolytic strepIn Canada, it was reported that 94% of 4-8-weektococci were ascribed to Lancefield groups R, S, RS, old clinically healthy piglets harbored S. suis in their and T in 1963.5 Other investigators working with capnasal cavities, and 79% of these isolates did not belong sulated streptococci similar to de Moor’s groups S and to the 9 capsular types.3 Recently, we demonstrated R realized that the polysaccharides involved in serothat almost 90% of these untypeable isolates belong to typing originated from the capsular material rather than only 4 of the new capsular types (types 17, 18, 19, and from the cell wall. They considered these isolates as a 21, unpublished data). Other investigators have atnew species (Streptococcus suis) within the Lancefield tributed the development of rhinitis4,7,22 to untypeable group D, with 2 capsular types: 1 and 2, respectively. S. suis isolates. At this time, it is not possible to know The de Moor’s group RS was also added as S. suis type whether any of the capsular types of S. suis belong to 1⁄2.26 In 1983, 6 new capsular types of S. suis origithe normal flora of the nasal cavity or whether they nating from diseased pigs were described. 20 In 1987 represent real pathogens. Of the new capsular types, the species was officially recognized, l4 but the authors types 9 and 22 are more frequently found in diseased demonstrated by DNA hybridization that S. suis was pigs than in healthy ones. An outbreak of S. suis type not closely related to group D streptococci. 9 infection recently occurred in swine in Canada? Despite the presence of 9 capsular types of S. suis, Although 22 of 23 capsular types of S. suis are present untypeable isolates were still frequently reported. These in North America, our studies revealed that almost isolates were recovered from diseased4,10,12,13,22,24,25 and 30% of isolates recovered from diseased pigs are still clinically healthy pigs.2,3,21 More recently, 14 new capuntypeable (unpublished data). sular types have been described.9 Some of the reference As the number of capsular types increases, serotypstrains originated from diseased pigs, whereas others ing becomes more complicated, and it could soon bewere from the nasal cavities of clinically healthy pigs. come limited to reference laboratories. Even biochemOne strain was isolated from a diseased calf (capsular ical identification, when used alone, can be misleading. type 20) and another from a human case of meningitis Thus, veterinary diagnostic laboratories face a difficult (capsular type 14). Isolates belonging to capsular type situation. There is an urgent need for a standardization 14 have recently been recovered from diseased pigs in of both the biochemical identification of S. suis and our laboratory as well as in Denmark and Belgium (Dr. the techniques for capsular typing. The purpose of this J. Henrichsen, personal communication, 1989). This paper is to summarize the knowledge of biochemical confirms that types other than capsular type 2 could characterization and serotyping of S. suis and to suggest be involved in a zoonosis.9 In addition to the bovine means to facilitate the proper identification of this incapsular type 20, several other S. suis isolates have fectious agent of growing importance. been recovered from ruminants.9,12 Capsular type 16 Streptococcus suis is a gram-positive coccus that ocwas recently isolated in our laboratory from lungs of curs singly, frequently in pairs, or occasionally in short a calf suffering from bronchopneumonia, and a capchains. The organism grows well in aerobiosis, but growth is often enhanced by microaerophilic condiFrom the Research Group in Swine Infectious Diseases, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, tions. The majority of strains are alpha-hemolytic on

Organizational Configurations: Cohesion, Change, and Prediction

Abstract: Recent studies have argued that the variety of organizational forms is limited and that certain common organizational configurations-alignments among strategy, structure and environment-occur with remarkable frequency and account-for a very significant fraction of organizations. This has been demonstrated empirically. The purpose of this paper is to probe into the cohesion, dynamics, and predictive implications of configurations. Ten propositions are derived by analyzing some representative configurations. It is proposed that the constrained variety and cohesion of configurations are caused by the interdependent, robust, cyclical, and reciprocal relationships among their parts. It is also argued that configurations vary in their first-order changes, but that all resist second-order changes, that is, changes in the direction of evolution. This makes them prone to long periods of momentum punctuated by brief periods of revolution. Finally, configurations are shown to vary in their internal relationships so ...

Surgical management of giant pituitary adenomas

Abstract: During the past 25 years, 77 giant pituitary adenomas have been treated surgically, including suprasellar extensions of type C in 66 cases and of type D in 11 cases. Non-secreting adenomas were present in 53 and secreting adenomas in 24 cases. All patients except 3 presented with significant visual field defects; including bitemporal hemianopia, superior quadranopia or unilateral temporal hemianopia, contralateral blindness in 73% of the cases, and one case with sudden bilateral blindness due to acute pituitary apoplexy. A single transsphenoidal procedure was carried out in 74% of the patients while 11 patients (7%) required re-operations for recurrent or residual tumor. Only 3 patients required a subsequent transcranial procedure. Complications included 1 CSF-leak, 1 empty-sella syndrome and 4 fatal post-operative hematomas. We prefer the transsphenoidal route even in very large or giant pituitary adenomas, since it allows rapid and adequate decompression of the optic nerves and chiasm, avoids major pituitary insufficiency in 60% of the cases and is associated with low morbidity-mortality rates.

Thiamine-dependent enzyme changes in temporal cortex of patients with Alzheimer's disease

Abstract: Activities of thiamine-dependent enzymes [pyruvate dehydrogenase (PDHC), alpha-ketoglutarate dehydrogenase (alpha KGDH), and transketolase (TK)] were measured in autopsied samples of temporal cortex from six patients with Alzheimer's disease and from eight age-matched control subjects who were free from neurological or psychiatric diseases. Times from death to freezing of dissected material at -70 degrees C were matched. Significant decreases in PDHC (decreased by 70%; P less than 0.01), alpha KGDH (decreased by 70%; p less than 0.01), and TK (decreased by 52%; P less than 0.01) were observed in brain tissue from patients with Alzheimer's disease. In contrast, activities of glutamate dehydrogenase were within normal limits. These findings suggest a possible role for alterations of brain thiamine metabolism or utilization in Alzheimer's disease.

Cellular location of a Treponema denticola chymotrypsinlike protease and importance of the protease in migration through the basement membrane.

Abstract: A number of immunological methods were used to localize a cell-associated Treponema denticola chymotrypsinlike protease. Indirect immunofluorescence staining, immunogold labeling, and an enzyme-linked immunosorbent assay all indicated that the protease was attached to the outside of the cell envelope. The invasive capability of T. denticola was evaluated by following the degradation of a reconstituted basement membrane material (Matrigel) and the release of spirochetes from the gel. Under conditions where the chymotrypsinlike activity was increased, more spirochetes migrated from the gel. Protease inhibitors strongly reduced the number of cells that moved out of the gel. The purified chymotrypsinlike protease degraded the basement membrane components type IV collagen, laminin, and fibronectin. The study suggests that the T. denticola chymotrypsinlike protease may play an important role in the invasion and destruction of basement membrane.

Ediacaran remains from intertillite beds in northwestern Canada

Abstract: A turbidite sequence within the Twitya Formation (Windermere Supergroup) in the ackenzie Mountains, northwestern Canada, has yielded an assemblage composed of simple centimetric annuli and discs, which are interpreted as biogenic and referred to Nimbia occlusa Fedonkin, Vendetta ? sp., and Irridinitus ? sp. They occur below a glaciomarine diamictite about 2.5 km below the base of the Cambrian, and they may represent the oldest Ediacaran fossils now known. The find has implications for models that relate the evolution of the Ediacara fauna to the waning of the Varanger glaciation.

Quantitative Methods and Biogeographic Analysis

Abstract: Numerical methods are presented that represent three different approaches to biogeographic problems. The first approach is multivariate data analysis. The delineation of biogeographic “provinces” or areas is a type of descriptive analysis that can be accomplished by clustering faunal data (with or without spatial contiguity constraint) and drawing the resulting choropleth map. On the other hand, ecological biogeographers like to use ordinations of sampling localities and interpret the main axes of variation in terms of environmental gradients; canonical ordination, where a species presence or abundance data table and an environmental data matrix are both analyzed simultaneously, can be used with profit in this context. Secondly, the analysis of spatial patterns can help identify the type of spatial distribution of the biological material, both at the population and at the community level, while Mantel tests and other derived analyses make it possible to test hypotheses concerning causal factors possibly responsible for the observed spatial structures. Finally, phylogenetic-tree reconstruction methods, as well as other techniques, can be used for historical biogeographic studies; these include the study of taxa cladograms and of area cladograms.

Monitoring spatial variability of forest interception

Abstract: Field instrumentation was designed and installed to quantify the influence of forest interception on the spatial and temporal distribution of water flux onto and into the forest soil at the plot scale. An application is presented which demonstrates that the instrumentation has the required resolution to monitor the spatial variability and dynamics of the flux processes. The observations show that spatial variability of interception may play an important role, not only in small scale soil moisture heterogeneity, but also in the hydrological response of a forested catchment at the hillslope scale. They also highlight the need of gathering more field information on the effects of vegetation on the spatial variability of soil surface water input.