Showing papers by "Memorial University of Newfoundland published in 1989"

Viscerotopic representation of the upper alimentary tract in the rat: sensory ganglia and nuclei of the solitary and spinal trigeminal tracts.

Abstract: The aim of this study was to map the viscerotopic representation of the upper alimentary tract in the sensory ganglia of the IXth and Xth cranial nerves and in the subnuclei of the solitary and spinal trigeminal tracts. Therefore, in 172 rats 0.5-65 microliters of horseradish peroxidase (HRP), wheat germ agglutinin-HRP, or cholera toxin-HRP were injected into the trunks and major branches of the IXth and Xth cranial nerves as well as into the musculature and mucosa of different levels of the upper alimentary and respiratory tracts. The results demonstrate that the sensory ganglia of the IXth and Xth nerves form a fused ganglionic mass with continuous bridges of cells connecting the proximal and distal portions of the ganglionic complex. Ganglionic perikarya were labeled in crude, overlapping topographical patterns after injections of tracers into nerves and different parts of the upper alimentary tract. After injections into the soft palate, pharynx, esophagus, and stomach, anterograde labeling was differentially distributed in distinct subnuclei in the nucleus of the tractus solitarius (NTS). Palatal and pharyngeal injections resulted primarily in labeling of the interstitial and intermediate subnuclei of the NTS and in the paratrigeminal islands (PTI) and spinal trigeminal complex. Esophageal and stomach wall injections resulted in labeling primarily of the subnucleus centralis and subnucleus gelatinosus, respectively. The distribution of upper alimentary tract vagal-glossopharyngeal afferents in the medulla oblongata has two primary groups of components, i.e., a viscerotopic distribution in the NTS involved in ingestive and respiratory reflexes and a distribution coextensive with fluoride-resistant acid-phosphatase-positive regions of the PTI and spinal trigeminal nucleus presumably involved in visceral reflexes mediated by nociceptive or chemosensitive C fibers.

Modality effects and the structure of short-term verbal memory

Abstract: The effects of auditory and visual presentation upon short-term retention of verbal stimuli are reviewed, and a model of the structure of short-term memory is presented. The main assumption of the model is that verbal information presented to the auditory and visual modalities is processed in separate streams that have different properties and capabilities. Auditory items are automatically encoded in both the A (acoustic) code, which, in the absence of subsequent input, can be maintained for some time without deliberate allocation of attention, and a P (phonological) code. Visual items are retained in both the P code and a visual code. Within the auditory stream, successive items are strongly associated; in contrast, in the visual modality, it is simultaneously presented items that are strongly associated. These assumptions about the structure of short-term verbal memory are shown to account for many of the observed effects of presentation morality.

Repeated exposures intensify rather than diminish the rewarding effects of amphetamine, morphine, and cocaine

Abstract: It is commonly believed that repeated exposures diminish the pleasurable effects of drugs and hence that pleasure must have only a minor role in addiction. In six experiments with rats, repeated exposures to amphetamine, morphine, or cocaine were found to enhance the drug-induced rewarding effect as measured by conditioned place preference. Thus, sensitization to the rewarding effect, rather than tolerance, was obtained. Also, cross-sensitization was obtained; exposures to amphetamine enhanced the rewarding effect of morphine and vice versa; similarly, exposures to morphine enhanced the rewarding effect of cocaine. These findings support a new theory: drugs of abuse are addictive because repeated exposures sensitize the central reward mechanism so that drug taking produces a progressively greater reinforcing effect each time it occurs.

Influence of maternal diet during lactation and use of formula feeds on development of atopic eczema in high risk infants.

Abstract: OBJECTIVE--To examine the effects of maternal diet during lactation and the use of formula feeds on the development of atopic eczema in infants at risk. DESIGN--Mothers who planned to breast feed exclusively were randomly allocated to either a restricted diet (avoiding milk and other dairy products, eggs, fish, peanuts, and soybeans) or a diet without restrictions. Mothers who did not plan to breast feed were randomly allocated to using one of three formula feeds. SETTING--Child health centre in Canada. SUBJECTS--97 Mothers who chose to breast feed and 124 mothers who did not. INTERVENTIONS--Restricted diet for 49 mothers who breast fed. Casein hydrolysate formula, soy milk formula, or cows' milk formula for infants not breast fed. MAIN OUTCOME MEASURE--Development of eczema in babies. RESULTS--Infants were followed up over 18 months and examined for eczema. Eczema was less common and milder in babies who were breast fed and whose mothers were on a restricted diet (11/49 (22%) v 21/48 (48%)). In infants fed casein hydrolysate, soy milk, or cows' milk 9/43 (21%), 26/41 (63%), and 28/40 (70%), respectively, developed atopic eczema. CONCLUSIONS--In families with a history of atopic disease [corrected] mothers who breast feed should avoid common allergenic foods during lactation. If they choose not to breast feed a hydrolysate formula should be used.

Effect of feeding whey hydrolysate soy and conventional cow milk formulas on incidence of atopic disease in high risk infants.

Abstract: The effect of feeding different infant formulas on incidence of atopic disease was assessed in a prospective double-blind randomized controlled trial among "high risk" infants with family history of atopy among first-degree relatives The incidence of atopic eczema, wheezing, rhinitis, gastrointestinal symptoms, and colic was noted and serum IgE antibodies to milk were estimated Seventy-two infants were recruited into each of the following groups: cow milk whey hydrolysate formula (NAN/HA), conventional cow milk formula (Similac), soy-based formula (Isomil), and exclusive breast feeding for greater than or equal to 4 months The number of infants who exited for reasons other than atopy and were excluded from analysis were 4, 5, 4, and 12 in the four groups, respectively The incidence of one or more symptoms of possible allergic etiology was five of 68 infants fed NAN/HA, 24 of 67 infants fed Similac, 25 of 68 infants fed Isomil, and 12 of 60 breast-fed infants Among symptomatic infants, skin prick test to milk proteins was positive in four out of five infants fed NAN/HA, 16 of 24 fed Similac, 2 of 25 fed Isomil, and 7 of 12 breast-fed IgE antibodies to milk were found in 2 of 68, 9 of 67, 0 of 68, and 6 of 60 infants in the four groups, respectively It is concluded that exclusive breast feeding for more than 4 months is partially protective against the development of atopic disease among high risk infants(ABSTRACT TRUNCATED AT 250 WORDS)

Density-dependent habitat selection: Testing the theory with fitness data

Abstract: According to density-dependent habitat selection theory, reproductive success should decline with increased density. Fitness should be similar between habitats if habitat selection follows an ideal free distribution; fitness should be dissimilar between habitats if habitat selection is modified by territorial behavior. I tested these assumptions by examining a variety of fitness estimates obtained from white-footed mice living in nest boxes in forest, forest edge and fencerow habitats in southwestern Ontario. As expected, mean litter size declined with increased population density. Litter sizes, adult longevity and the proportion of adult animals in breeding condition were not significantly different among the three habitats. The success at recruiting at least one offspring to the adult population and the number of recruits per litter were much greater in the forest than in either of the other two habitats. Fitness was thus unequal among habitats and the results confirm both assumptions of density-dependent habitat selection theory for territorial white-footed mice.

Median Estimation in the Presence of Auxiliary Information

Abstract: SUMMARY This paper deals with the estimation, under simple random sampling, of a finite population median in the presence of an auxiliary variable An estimator which is a simple modification of the ratio estimator for the mean is studied along with two other proposed estimators derived from a different approach These estimators are applicable in situations where only the population median or a grouped frequency distribution of the auxiliary variable is known On the basis of the asymptotic properties derived and some simulation results, the efficiencies of these estimators are compared It is shown that the two estimators proposed, unlike that obtained from modifying the ratio estimator, always dominate the sample median in mean-squared error and that their efficiencies depend directly on the probability of 'concordance' rather than on the validity of a linearity assumption between the survey variable and the auxiliary variable When the linearity assumption is approximately satisfied, the three estimators are seen to have comparable efficiencies, while the modified ratio estimator is found to be quite sensitive to departures from the linearity assumnption

Raman frequency and intensity studies of liquid H2O, H218O and D2O

Abstract: Raman frequency and intensity measurements have been performed on liquid water as HO, DO and HO to study the effects of isotope substitution. Intensity data were collected digitally, normalized to account for the temperature and frequency factors and presented in isotropic and anisotropic forms. The frequency and intensity changes are consistent with the predictions of simple reduced mass calculations. In particular, there was no evidence to support the reported breakdown of the Born—Oppenheimer approximation as has been reported for HO. The isotope invariant sum rule was checked for HO, HO and DO by relative intensity studies for the OH stretching region against an internal sulfate reference peak. Identical values for the isotope invariant sum were obtained for HO and HO but the value for DO was about 30% larger. The difference appears to have its origin in the more highly structured nature of DO due to smaller anharmonic effects. Accurate frequency shifts among HO, HO and DO are also presented. Surprisingly, the greatest frequency shift which accompanied O substitution was in the low‐frequency hydrogen‐bonded region where the band at 192 cm for HO shifted by 15 cm to 177 cm for HO. This result confirms previous observations and establishes the origin of this band as a hydrogen‐bonded symmetric stretching mode which involves primarily oxygen displacement. Further support for this assignment comes from the observation that the band at 192 cm is slightly polarized. The effects of intermolecular coupling contribute to the band structure of the internal modes. Frequency differences in the OH stretching region of HO and HO suggest that only about 50% of the anisotropic intensity is due to the Raman activity of the ν antisymmetric stretching mode while the remainder is due to the symmetric stretching modes of intermolecularly coupled water molecules. A point‐by‐point comparison of the OH stretching region for the isotropic scattered intensity of HO and HO revealed that the complete region from 2800 to 3800 cm was shifted equally by 7 cm, a fact that suggests that the peak maximum at about 3250 cm is just part of the ν symmetric stretching mode and is not primarily due to 2ν. The effect of intermolecular coupling in the ν region of liquid water was confirmed by the difference in the frequency for the isotropic and anisotropic components for each of the isotopic forms of water. For HO the peak maximum in the isotropic spectrum was at 1619 cm whereas the peak maximum in the anisotropic spectrum was at 1637 cm with the result that in the measured I spectrum the peak maximum was at 1629 cm. Copyright

Can We Test Validly for Critical Thinking

Abstract: This paper focuses first on two questions: (a) Is critical thinking generalizable? and (b) What is a critical thinking disposition? It is argued that the controversial nature of these questions limits the ability to judge the validity of critical thinking testing. Following this discussion, the paper outlines a series of procedures that can help increase the validity of one fundamental aspect of critical thinking testing–multiple-choice testing of credibility judgment. The procedures rely on verbal reports of examinees’ thinking on items to gain direct evidence on the reasons for their answer choices. It is recognized that multiple-choice tests cannot test all important aspects of critical thinking, but that improving multiple-choice tests where they are applicable can have important practical and scientific implications.

Propulsion of a fin whale (Balaenoptera physalus): why the fin whale is a fast swimmer.

Abstract: Measurements of an immature fin whale (Balaenoptera physalus). which died as a result of entrapment in fishing gear near Frenchmans Cove. Newfoundland (47$^\circ$ $9'$ N. 55$^\circ$ $25'$ W), were made to obtain estimates of volume and surface area of the animal. Detailed measurements of the flukes, both planform and sections, were also obtained. A strip theory was developed to calculate the hydrodynamic performance of the whale's flukes as an oscillating propeller. This method is based on linear, two-dimensional, small-amplitude, unsteady hydrofoil theory with correction factors used to acount for the effects of finite span and finite amplitude motion. These correction factors were developed from theoretical results of large-amplitude heaving motion and unsteady lifting-surface theory. A model that makes an estimate of the effects of viscous flow on propeller performance was superimposed on the potential-flow results. This model estimates the drag of the hydrofoil sections by assuming that the drag is similar to that of a hydrofoil section in steady flow. The performance characteristics of the flukes of the fin whale were estimated by using this method. The effects of the different correction factors, and of the frictional drag of the fluke sections, are emphasized. Frictional effects in particular were found to reduce the hydrodynamic efficiency of the flukes significantly. The results are discussed and compared with the known characteristics of fin-whale swimming.

Meiobenthos of the hatteras abyssal plain and Puerto Rico trench: abundance, biomass and associations with bacteria and particulate fluxes

Abstract: An abyssal station on the Hatteras Abyssal Plain (5411 m) and two hadal stations in the Puerto Rico Trench (7460 and 8189 m) were sampled to obtain quantitative information on the abundance and biomass of metazoan meiofauna and, for comparative purposes, bacteria and measurements of particulate flux rates. Average meiofauna abundance (no./10 cm2 ± 1 S.E. integrated over a sediment depth of 15 cm) was lowest at the 7460 m site (44 ± 10) and highest at the 8189 m (96 ± 15) and Hatteras sites (114 ± 26), the latter two not being statistically significant from each other. Biomasses (μg dry wt/10 cm2 ± 1 S.E., also integrated over a 15 cm depth) at the Hatteras and 7460 and 8189 m Trench sites were 38.4 ± 10.3, 3.8 ± 1.6 and 14.3 ± 5.1, respectively; all differences were statistically significant. High biomass at the Hatteras site was due to large, burrowing harpacticoid copepods that were found to depths of 10–15 cm below the sediment surface, and which were most abundant below the surface (0–2 cm) layer of sediment. Nematodes, the numerically dominant taxon, were most abundant in the upper 6 cm of sediment at all sites, as were copepods at the two Trench sites. Average abundances of bacteria (no. of cells × 109 per 10 cm2 of sediment to a depth of 15 cm), determined by epifluorescence microscopy, were 11.0, 10.5 and 5.6 at the Hatteras, 7460 and 8189 m Trench sites, respectively. Flux rates of organic carbon and total nitrogen (mg m−2 day−1) were about four times higher at the Hatteras site (e.g. 25.8 and 3.8) than at the 7460 m site in the Trench (6.3 and 0.8). An analysis of the meiofaunal and bacterial abundances obtained at the three sites revealed no significant associations between the two organismal groups, though abundances of both groups did decrease significantly and predictably with sediment depth at each station. Associations between particulate flux rates and meiofauna biomass were highly significant, suggesting that flux rates measured in near-bottom traps may be useful indicators of general resources available to the meiobenthos.

The interaction of the cardioprotective agent ICRF-187 [+)-1,2-bis(3,5-dioxopiperazinyl-1-yL)propane); its hydrolysis product (ICRF-198); and other chelating agents with the Fe(III) and Cu(II) complexes of adriamycin.

Abstract: Membrane-permeable ICRF-187 ((+)-1,2-bis(3,5-dioxopiperazinyl-1-yl)propane) has shown promise as a cardioprotective agent against adriamycin-induced cardiotoxicity. ICRF-187 may act through its rings-opened hydrolysis product (ICRF-198) which has an EDTA-type structure and, likewise, strongly binds metal ions. The reactions of these compounds with Fe3+-adriamycin, and Cu2+-adriamycin complexes were examined. ICRF-198 quickly and completely removed both Fe3+ and Cu2+ from their complexes with adriamycin. ICRF-187 also reacted directly., but more slowly, with Fe3+-adriamycin to remove Fe3+ from the complex. This reaction was first order in ICRF-187 and Fe3+-adriamycin and yielded a second order rate constant of 123M−1 min−1. Metal ion-complex promoted hydrolysis may thus contribute to thein vivo hydrolysis of ICRF-187 to its metal ion-chelating active rings-opened form. Both ICRF-187 and ICRF-198 were very effective in preventing the Fe3+-adriamycin induced inactivation of the cytochromec oxidase activity of submitochondrial particles. A number of other chelating agents (desferal; pencillamine; DTPA; EDTA; TPEN; bathophenanthroline sulfonic acid; 2,2'-bipyridine; 1,10-phenanthroline, glutathione and 2-mercaptoethanol) were also examined for their ability to remove Fe3+ and Cu2+ from their complexes with adriamycin.

A review of genetic variation in Atlantic salmon, Salmo salar L., and its importance for stock identification, enhancement programmes and aquaculture

Abstract: The increasing exploitation of Atlantic salmon as a food source and sport fish demands a better understanding of salmon genetics and the dynamics of Atlantic salmon populations. Surveys of salmon populations for protein electrophoretic variation reveal that the average heterozygosity in Salmo salar is low and that four gene loci account for more than 95% of the total electrophoretically detectable variation. Populations that have been studied by this means fall into one of three groups: Western Atlantic, Eastern Atlantic or Baltic. However, biochemical genetics involving starch gel electrophoresis cannot be used routinely to identify the continent of origin of an Atlantic salmon, let alone its native river. The mitochondrial genome can be used to identify North American or European salmon with the aid of restriction endonucleases that have six base pair recognition sites. Restriction endonucleases that recognize four base pairs appear to be able to identify salmon from a particular river system. There has been a move from protein variation to mitochondrial DNA variation and this will inevitably lead to more extensive studies on the nuclear genome. Chromosomal studies suggest differences between salmon from Europe and North America but these have been hampered by lack of good banding procedures. Preliminary studies using cloned segments of salmonid genomes suggest that repeated sequences such as the genes for ribosomal RNA will be most useful for identifying specific stocks of Atlantic salmon. The need for continued genetic studies on the Atlantic salmon and the relevance and importance of the results of this research for stock identification, enhancement programmes, aquaculture and basic science are discussed.

The individual and society.

Abstract: Etude du role du psychiatre dans le conflit qui oppose l'individu a la societe. Ce role est envisage aussi dans les cas de cooperation entre psychiatres et institutions gouvernementales (armee…)

A Controlled Evaluation of Reminiscence and Current Topics Discussion Groups in a Nursing Home Context

Abstract: In this randomized study, we compared the psychological well-being of elderly nursing home residents who participated in reminiscence and current topics group discussions with a control group of residents. We rated participants happiness/depression, activity, mood, and functional levels before and after the group interventions. The intervention had a significant effect only on the happiness/depression measure, with both intervention groups showing positive changes compared to the control group.

The feeding, growth and behaviour of juvenile cod, Gadus morhua L., in cold environments

Abstract: Most studies on feeding-related activities of fish in cold water (0° C) have not used eurythermal species or examined a broad suite of activities. In this study we report on the feeding, growth, behaviour and conversion-efficiency of 0 + Atlantic cod in response to water temperature and food availability. In one experiment, activity, opercular beat and growth decreased with decreasing temperature over the range 8·3–0·6° C. However, the conversion efficiency increased with decreasing temperature, a result partly explained by the relative change in activity and opercular rate. In another experiment, temperature had a linear effect on growth in cod fed different food rations. Both food availability and temperature were found to influence growth in group 0 + cod. The specific growth rate of cod in this experiment exceeded 2% day-1. Growth data collected from cod sampled in the field during the cold-water period showed a progressive increase of mean length over the season. Overall, these results demonstrate that 0 + cod have adapted to life in cold-water environments, in contrast to adult cod which mostly inhabit warmer environments.

Late Pleistocene terrestrial deposits on the continental shelf of western Canada: Evidence for rapid sea-level change at the end of the last glaciation

Abstract: A paleosol with in situ rooted plant remains has been found in a core at a water depth of 95 m on the central continental shelf of British Columbia. Fluvial sediments associated with the paleosol are sharply overlain by lagoonal or shallow pond sediments; these, in turn, are overlain by shallow-marine ediments. Radiocarbon dates on wood fragments and root recovered from the cored sediments indicate that relative sea level was at least 95 m lower 10,500 yr B.P. and that the core site was rapidly transgressed by the sea shortly thereafter. This rapid transgression was contemporaneous with an equally rapid regression at the heads of fiords on the British Columbia mainland to the east. The two are probably genetically linked and a result of late Pleistocene deglaciation and the migration and collapse of a glacial forebulge. Our evidence indicates that large areas of the British Columbia continental shelf were subaerially exposed 11-10 ka. This may have facilitated the southward migration of early humans from Beringia into mid-continental North America at the end of the Pleistocene.

Development of a health questionnaire specific for end-stage renal disease.

Abstract: To compare the efficacy of various end-stage renal disease (ESRD) therapies valid and reproducible probes which measure well-being and are specific for ESRD are necessary. Four studies were undertaken to provide and test these probes. (1) 107 dialysis and 119 transplant recipients were interviewed to determine the prevalence of 24 physical symptoms. (2) A questionnaire was devised using 2 new indexes (a symptom scale derived from the first study using 12 symptoms and an affect scale comprising 12 emotions) and 6 indexes previously used in other chronic illnesses. Interobserver and intraobserver reproducibility was satisfactory. (3) Construct validity for the questionnaire was shown by interviewing 97 dialysis and 82 transplant patients in whom we hypothesized that physical well-being would be better in transplant patients. After age matching the transplant group was more active, with a higher objective quality of life and fewer physical symptoms than the dialysis group. (4) 63 stable dialysis, 67 stable transplant, 15 dialysis patients successfully transplanted in the intervening year and 5 failed transplanted patients were reinterviewed 1 year later to assess the responsiveness of the questionnaire. In the group who had recently been successfully transplanted both physical, affect and quality of life scores showed a major improvement following transplant. We conclude that this questionnaire is specific for ESRD, examines physical, psychological, and social well-being, is brief, easily administered, reproducible, has construct validity and is responsive to changes in therapy.