Showing papers by "Memorial University of Newfoundland published in 1990"

The Diagnosis and Prognosis of Autosomal Dominant Polycystic Kidney Disease

Abstract: Background. Autosomal dominant polycystic kidney disease is usually caused by a mutant gene at the PKD1 locus on the short arm of chromosome 16, but in about 4 percent of families with the disorder it is caused by unknown mutations elsewhere in the genome. The natural course of the disease in both genetic forms is not well characterized. Methods. We studied 17 families with autosomal dominant polycystic kidney disease to compare presymptomatic diagnosis by ultrasonography with diagnosis by genetic-linkage studies and to relate clinical variation of the disease to whether the PKD1 mutation was implicated. Results. In 10 families the disorder was found to cosegregate with polymorphic DNA markers flanking the PKD1 locus, in 2 families it did not, and in 5 families linkage could not be determined. In the 10 families with the PKD1 mutation, 46 percent of the members less than 30 years old who had a 50 percent risk of inheriting a mutation had renal cysts, as compared with 11 percent of the members of ...

Renal arginine synthesis: studies in vitro and in vivo.

Abstract: Renal arginine synthesis is a major endogenous source of arginine. Argininosuccinate lyase occurs almost exclusively in kidney cortex. In studies with isolated renal cortical tubules, we observed rapid rates of arginine synthesis from citrulline, provided a source of the N atom of the guanidino group of arginine was supplied. Aspartate, glutamate, or glutamine were effective, whereas glycine, alanine, serine, or NH4Cl were ineffective as this second substrate. Arginine synthesis as a function of citrulline concentration was determined and was found to be highly sensitive to citrulline concentrations in the physiological range (60 microM), suggesting that renal arginine synthesis in vivo could be regulated by circulating citrulline levels. Therefore, arginine synthesis by the kidney was investigated in vivo by measuring the net flux of citrulline and arginine in saline-infused (control group) and citrulline-infused rats. In normal animals, uptake of citrulline was 60.5 +/- 20.7 nmol.min-1.100 g body wt-1, and a similar arginine release was observed. Citrulline infusion that increased circulating citrulline levels fourfold resulted in a similar increase in renal citrulline uptake (224 +/- 33 nmol.min-1.100 g-1) and a similar increase in renal production of arginine. The results suggest that the availability of citrulline is a limiting factor for renal arginine synthesis in rats.

Cellular structures in topology

Abstract: 1. The fundamental properties of CW-complexes 2. Categories of CW-complexes 3. Polyhedra and simplicial complexes 4. Simplicial sets 5. Spaces of the homotopy type of a CW-complex Appendixes.

MK-801 and AP5 impair acquisition, but not retention, of the Morris milk maze.

Abstract: The effects of the NMDA blockers, AP5 and MK-801, were assessed in two spatial tests. AP5 (10 μg in 2 μl ICV, N=6), or MK-801 (0.07 mg/kg IP, N=6), significantly increased open-field activity in male Long-Evans rats in two 3-min tests (Days 1 and 2) compared to control groups receiving equal volume saline injections (N=12). In the Morris milk maze, NMDA blockade significantly impaired acquisition performance on two bblocks of six trials, which followed each open-field test. Only control animals showed evidence of acquisition on a drug-free retention test assessing latency to reach the expected platform area and number of crossings in the area on Day 4. Retention was tested in control animals under NMDA blockade on Day 6. There was no effect of NMDA blockade on retention in the Morris milk maze. These results support the hypothesis that NMDA receptors are critical for the initiation of synaptic modification underlying place learning, but are not necessary in synaptic transmission during retrieval of place information.

The clinical course of left ventricular hypertrophy in dialysis patients.

Abstract: To determine the clinical and echocardiographic outcome of left ventricular hypertrophy a prospective study was undertaken of 104 nondiabetic dialysis patients without dilated cardiomyopathy, who were

U/Pb zircon and baddeleyite ages for the Palisades and Gettysburg sills of the northeastern United States: Implications for the age of the Triassic/Jurassic boundary

Abstract: Zircons extracted from the Palisades and Gettysburg sills and baddeleyite from the Palisades sill yield consistent U-Pb ages of 201 ±1 Ma. These sills are likely related to the lowermost basalt flows of the Late Triassic-Early Jurassic Newark Supergroup rift basins of the eastern margin of North America (because of the geochemical similarity of their high-Ti quartz tholeiites and because drilling suggests that the Palisades sill directly fed some of the lowermost flows). Because the lowermost flows of the Newark Supergroup are paleonto-logically assigned to the lowermost Hettangian, the 201 ±1 Ma age of the sills should be slightly younger than the age of the Triassic/Jurassic boundary. Our data support the age of 204 ±4 Ma assigned the Triassic/Jurassic boundary and suggest that recent K-Ar dating for the Hettangian flows of the Newark Supergroup, which yielded an average age of 190 ±3 Ma, is about 5% low.

Micronutrients and immune functions. An overview.

Abstract: Given the worldwide prevalence of deficiencies of vitamins and trace elements, the consistent effects of undernutrition on immune responses, and the causal association of impaired immunocompetence and infection, micronutrient deficiencies are probably the most frequent cause of secondary immunodeficiency and infection-related morbidity. Much of the early work on nutrition and immunity was based on observations in young children in developing countries. It has become clear, however, that such data are equally applicable to other age groups and that nutritional deficiencies are not uncommon in any country. Many micronutrients play important roles in key cellular and metabolic processes. It is not surprising, then, that micronutrient deficiencies would alter immune responses. This has been amply verified in recent investigations in man and laboratory animals. The severity of immunologic impairment depends upon the severity of micronutrient deficiency, its interactions with other essential nutrients, age of the subject, and presence of concomitant infection. It must be emphasised that excessive intake of many micronutrients may also exert deleterious effects. The detailed description of the effects of individual nutrients on immunologic responses is given in subsequent contributions in this volume and in reviews published elsewhere. 1-10 In this selective overview, I advance four general concepts. One, alterations in immune responses occur early in the course of reduction in micronutrient intake and in body stores. Two, immunologic abnormalities predict outcome, particularly the risk of infection and mortality. Three, in the case of many micronutrients, excessive intake is associated with impaired immune responses. Four, tests of immunocompetence are useful in titration of physiologic needs and in assessment of safe lower and upper limits of intake of micronutrients.

Clinical assessment of blood pressure.

Abstract: This study was performed to determine the blood pressure measuring techniques and accuracy of sphygmomanometers used by physicians in ambulatory care clinics on the Avalon Peninsula of Newfoundland. Of the 114 participating physicians, no physician completely followed all the recommended BP measuring techniques of the American Heart Association. Almost all physicians supported the patient's arm at heart level to measure BP. Fewer physicians used the following recommended techniques; palpation to initially assess systolic BP (38%), measurement of BP in both arms (23%), an appropriate rate of cuff deflation (18%), measurement of BP in recommended patient positions (10%), the appropriate length of rest (4%) or use of a cuff of appropriate size (3%). Approximately 8% of mercury sphygmomanometers were out of calibration by at least 4 mmHg but none were out by more than 6 mmHg. Forty percent of aneroid sphygmomanometers were out of calibration by at least 4 mmHg and of these 30% were out by 10 mmHg or more. Mercury and aneroid sphygmomanometers were used by 60% of physicians. Aneroid sphygmomanometers were used exclusively by 34% of physicians, while 5% of physicians relied solely on mercury devices. Standardized techniques for BP measurement are not used and inaccurate sphygmomanometers are common; these factors may lead to misclassification of blood pressure and inappropriate treatment of patients.

The Annual Energetics Cycle of Little Penguins (Eudyptula Minor)

Abstract: Isotope turnover techniques were used to measure the metabolic and food consumption rates of free—living Little Penguins (Eudyptula minor) throughout the annual cycle in Bass Strait, Australia. Water and sodium flux rates were also measured, and all parameters showed significant seasonal differences. There were no differences between male and female adult Little Penguins in any of the parameters measured. The estimates of energy turnover were used to construct time/energy budgets for comparison with time/activity budgets. Although chick—rearing occupies only 16% of the annual time budget, this period is the most energetically expensive phase and accounts for 31% of the annual energy budget. The high energy costs of chick—rearing are particularly extreme toward the end of chick growth. At this time the daily rates of food consumption by attending adults exceed 60% of adult body mass. During the nobreeding season (winter) adult energy expenditure exceeds that acquired from feeding, and the birds lose body mass. The metabolic costs of pursuit diving appear to be similar to those associated with flapping flight. The total annual food requirements of Little Penguins in Bass Strait were estimated to be 37 000 Mg of food (fish, squid and krill). The penguins are most vulnerable to fluctuations in food availability, either as a result of natural perturbations or from commercial fishing activities, during the winter and during the chick—rearing phase of breeding. _kw Albatross Island, Tasmania

Systematic Training of Graduate-Level Counselors Narrative and Meta-Analytic Reviews of Three Major Programs

Abstract: This study reviews research on Carkhuff's Human Resource Training/Human Resource Development (HRT/HRD), Kagan 's Interpersonal Process Recall (IPR), and Ivey's Microcounseling (MC) programs, in all of which the trainees were graduate-level counselors. Both narrative and meta-analytic reviewing approaches were used. What has been accomplished thus far in each program is summed up, and future directions for training and research are suggested. All three programs were found effective overall with the meta-analysis categorizing the effects of HRT/HRD as large, of IPR as small, and of MC as a medium. Beyond overall effects; the narrative and meta-analytic reviews tended to focus on different variables, calling reviewer and reader attention to differing concerns and recommendations. It was concluded that there is more work to be accomplished with all three training programs when used with graduate-level counselors, and both methods of research integration should be understood for what they do and do not offer a...

The who, when and where of early narratives.

Abstract: To be well understood, narratives need to be embedded within appropriate contextual information. The early development of key orientation (participants, location and time) was traced with an 18-month longitudinal study of real-experience narratives produced by 10 children aged approximately 2–3; 6. Listener knowledge or inference was required to decode most named participants and many were not specified at all. There was no developmental improvement. Orientation to when was rare at first and involved formula words indiscriminately applied. There was steady developmental improvement in frequency as well as differentiation of time references. where information was more common at all ages, particularly when the narrated events occurred away from home. It also showed developmental improvement, but only for away-from-home locations. Overall, very young children can produce narratives in an unscaffolded context to adults unfamiliar with their experiences. The potential role of parental scaffolding in teaching orientation skills is discussed.

Analysis of biological reference materials, prepared by microwave dissolution, using inductively coupled plasma mass spectrometry

Abstract: A procedure has been developed for the analysis of biological materials by inductively coupled plasma mass spectrometry (ICP-MS). Fast, efficient and complete sample digestion is achieved by a combined microwave-nitric acid/open beaker-nitric acid-hydrogen peroxide procedure. The ICP-MS analysis is performed with an on-line five-element internal standard to correct for matrix and instrumental drift effects. Results are presented for 24 elements in three biological reference materials (National Institute of Standards and Technology Standard Reference Materials 5277a Liver and 1566 Oyster and International Atomic Energy Agency Certified Reference Material H4 Animal Muscle). For all elements significantly above the detection limit and reagent blank concentrations, good agreement exists between ICP-MS and certified values.

Visual acuity assessment from birth to three years using the acuity card procedure: cross-sectional and longitudinal samples.

Abstract: We used the Teller Acuity Cards (TAC) to test 7 groups of 20 healthy infants and children ranging in age from 1 week to 36 months We also tested 27 of these children at least twice within their first year We had two primary goals: (1) to provide normative data on the development of visual acuity as assessed with the new version of the TAC (Vistech, Inc) and (2) to investigate the predictive value of the TAC The results from the cross-sectional samples show that our estimates of visual acuity are consistent with those reported by other researchers who used earlier versions of the TAC The longitudinal data indicate that, on the average, an early estimate of visual acuity was not predictive of a later estimate, at least within the first year The results are discussed in terms of the usefulness of the TAC for testing normal and clinical populations

Parasitism in marine fish after chronic exposure to petroleum hydrocarbons in the laboratory and to the Exxon Valdez oil spill.

Abstract: Crude oil or its water soluble components are known to induce histopathological effects in fish following chronic exposure. Fish tend to harbor a variety of parasites, most of which under natural conditions cause little or no apparent harm. However, after chronic exposure to petroleum hydrocarbons, the prevalence and intensity of parasitism increases substantially. Trichodinid ciliates are mainly ectoparasitic protozoans on the fills of fish. Since a previous study showed that chronic exposure to crude oil fractions resulted in increased parasitism, a study was initiated to ascertain the relationship between trichodinid infections and exposure of fish to crude oil or its fractions in the laboratory and subsequently, in the Gulf of Alaska following the Exxon Valdez oil spill.

Seabirds and fronts: a brief overview

Abstract: Oceanographic fronts are the sites of enhanced physical and biological activity, including locally concentrated feeding by marine birds. Two general hypotheses relating marine birds to fronts have been developed. The first is that enhanced primary production at fronts increases prey supply through increased animal growth, reproduction, or immigration. The second is that prey patches develop at fronts either through behavioural responses of prey to thermal or salinity gradients, or through interaction between prey behaviour and circulatory patterns. Several recent studies support the second hypothesis. The first hypothesis, that birds benefit from enhanced primary production at fronts, has yet to be evaluated. We need a better understanding of trophic mechanisms at fronts in order to determine (1) the proportion of daily energy requirements extracted by predators at fronts; (2) the proportion of natural mortality of prey populations at fronts; and (3) the probability of contact between seabirds and point source pollutants.

Performance of large line-start permanent magnet synchronous motors

Abstract: A successful design of a 25 hp permanent-magnet synchronous motor using SmCo/sub 5/ and NdBFe magnets is presented. Expressions to predict the motor run-up and terminal performance are given. The rotor was tested for the straight interior rotor magnet arrangement. A record efficiency of over 94% was obtained at full load with a high power factor when the NdBFe magnets were used. The starting and synchronization were quick and smooth. There was no evidence of temperature limitations on the embedded rotor NdFBe magnets. A reasonable agreement between the computed and measured results was obtained. >

Vocalizations of the North Atlantic pilot whale (Globicephala melas) as related to behavioral contexts

Abstract: Vocalizations of free-ranging North Atlantic pilot whales were studied in different behavioral contexts to gain insight into the function and biological significance of different sound types. Simple whistles (with no frequency inflections) were heard more frequently when whales were “milling,” a restful behavior type. During “surface active” behavior, energetic, often coordinated activity probably representing feeding, many sound types, especially complex whistles (with more frequency inflections) and pulsed sounds, occurred with greater frequency than when this behavior was absent. Greater numbers of most whistle types were produced when whales were spread over a larger area and when more subgroups were present. Thus, in pilot whales, there is a significant relationship between their sounds and their behavior, with vocalizations possibly serving to maintain contact and coordinate movements of the herd.

Accurate, reproducible measurement of blood pressure

Abstract: The diagnosis of mild hypertension and the treatment of hypertension require accurate measurement of blood pressure. Blood pressure readings are altered by various factors that influence the patient, the techniques used and the accuracy of the sphygmomanometer. The variability of readings can be reduced if informed patients prepare in advance by emptying their bladder and bowel, by avoiding over-the-counter vasoactive drugs the day of measurement and by avoiding exposure to cold, caffeine consumption, smoking and physical exertion within half an hour before measurement. The use of standardized techniques to measure blood pressure will help to avoid large systematic errors. Poor technique can account for differences in readings of more than 15 mm Hg and ultimately misdiagnosis. Most of the recommended procedures are simple and, when routinely incorporated into clinical practice, require little additional time. The equipment must be appropriate and in good condition. Physicians should have a suitable selection of cuff sizes readily available; the use of the correct cuff size is essential to minimize systematic errors in blood pressure measurement. Semiannual calibration of aneroid sphygmomanometers and annual inspection of mercury sphygmomanometers and blood pressure cuffs are recommended. We review the methods recommended for measuring blood pressure and discuss the factors known to produce large differences in blood pressure readings.

Petrogenesis and paleotectonic history of the wild-bight-group, an ordovician rifted island-arc in central newfoundland

Abstract: The Wild Bight Group (WBG) is a sequence of early and middle Ordovician volcanic, subvolcanic and epiclastic rocks, part of the Dunnage Tectonostratigraphic Zone of the Newfoundland Appalachians. A detailed geochemical and Nd-isotopic study of the volcanic and subvolcanic rocks has been carried out to determine the geochemical characteristics of the rocks, interpret their palcotectonic environments and constrain their petrogenetic history. The lower and central stratigraphic levels of the WBG contain mafic volcanic rocks with island-arc geochemical signatures, including LREE-enriched are tholeiites with e Nd(t) =-0.1 to +2.2 (type A-I), LREE-depleted arc tholeiites with e Nd(t) =+5.6 to +7.1 (type A-II) and an unusual suite of strongly incompatible-element depleted tholeiites in which e Nd(t) ranges from-0.9 to +4.6 and is negatively correlated with147Sm/144Nd (type A-III). High-silica, low-K rhyolites occur locally in the central part of the stratigraphy, associated with mafic rocks of arc affinity, and have e Nd(t) =+4.7 to +5.4. The upper stratigraphic levels of the WBG dominantly contain rocks with non-arc geochemical signatures, including alkalic basalts with e Nd(t) =+4.6 to +5.5 (type N-I), strongly LREE- and incompatible element-enriched tholeiites that are transitional between alkalic and non-alkalic rocks with e Nd(t) =+4.4 to +7.0 (type N-II) and rocks with flat to slightly LREE-enriched patterns and e Nd(t) =+5.1 to +7.4 (type N-III). Rocks with non-arc and arc signatures are locally interbedded near the stratigraphic type of the WBG. Nd-isotopic data in the type A-I and A-II rocks are generally compatible with mixing/partial melting models involving depleted mantle, variably contaminated by a subducted crustally-derived sediment. The petrogenesis of type A-III rocks must involve source mixing and multi-stage partial melting, but the details are not clear. The geochemistry and Nd isotope data for types N-I, N-II and N-III rocks are compatible with petrogenetic models involving variable partial melting of a source similar to that postulated for modern oceanic island basalts. Comparison of the WBG with modern analogues suggests a 3-stage developmental model: stage 1) island-arc volcanism (eruption of type mafic volcancs); stage 2) arc-rifting (continued eruption of type A-I, A-I, eruption of types A-II and A-III mafic volcanics and high-silica, low-K rhyolites); and stage 3) back-arc basin volcanism (continued minor eruption of type A-I basalts, eruption of types N-I, N-II, N-III basalts). Stages 1 and 2 volcanism involved partial melting of subduction contaminated mantle, while stage 3 volcanism utilized depleted-mantle sources not affected by the subducting slab. This model provides a basis for interpreting coeval sequences in central Newfoundland and a comparative framework for some early Paleozoic oceanic volcanic sequences elsewhere in the Appalachian orogen.

On Parameterizing Vertical Mixing of Momentum in Non-eddy Resolving Ocean Models

Abstract: We investigate the consequence, at small Ekman number, of adding vertical mixing of momentum terms to the incompressible thermocline equations. We find that choosing the vertical eddy viscosity, ν = Af2/N2, where f is the Coriolis parameter and N is the local value of the buoyancy frequency, leads to isopycnal mixing of fQ, where Q is the reciprocal of potential vorticity, provided A is independent of the vertical coordinate. If, additionally, A is also independent of the north–south coordinate, then on a beta-plane, this implies homogenization of potential vorticity, q, within closed q-contours on isopycnal surfaces. This conclusion extends to spherical geometry if ν is also inversely proportional to β, the gradient of f with respect to latitude, i.e. ν = Af2/(N2β). The connection with the recent work of Gent and McWilliams and the consequences for coarse resolution numerical model studies are discussed.

Interaction between perdeuterated dimyristoylphosphatidylcholine and low molecular weight pulmonary surfactant protein SP-C.

Abstract: A low molecular weight hydrophobic protein was isolated from porcine lung lavage fluid using silicic acid and Sephadex LH-20 chromatography. The protein migrated with an apparent molecular weight of 5000-6000 on SDS-PAGE under reducing and nonreducing conditions. Gels run under reducing conditions also showed a minor band migrating with a molecular weight of 12,000. Amino acid compositional analysis and sequencing data suggest that this protein preparation contains intact surfactant protein SP-C and about 30% of truncated SP-C (N-terminal leucine absent). The surfactant protein was combined with perdeuterated dimyristoylphosphatidylcholine (DMPC-d54) in multilamellar vesicles. The protein enhanced the rate of adsorption of the lipid at air-water interfaces. The ability of the protein to alter normal lipid organization was examined by using high-sensitivity differential scanning calorimetry (DSC) and 2H nuclear magnetic resonance spectroscopy (2H NMR). The calorimetric measurements indicated that the protein caused a decrease in the temperature maximum (Tm) and a broadening of the phase transition. At a protein concentration of 8% (w/w), the enthalpy change of transition was reduced to 4.4 kcal/mol compared to 6.3 kcal/mol determined for the pure lipid. NMR spectral moment studies indicated that protein had no effect on lipid chain order in the liquid-crystal phase but reducedmore » orientational order in the gel phase. Two-phase coexistence in the presence of protein was observed over a small temperature range below the pure lipid transition temperature. Spin-lattice relaxation times (T1) were not substantially affected by the protein. Transverse relaxation time (T2e) studies suggest that the protein influences slow lipid motions.« less

Outcome of Congestive Heart Failure, Dilated Cardiomyopathy, Hypertrophic Hyperkinetic Disease, and Ischemic Heart Disease in Dialysis Patients

Abstract: Congestive heart failure in dialysis patients is associated with dilated cardiomyopathy, hypertrophic hyperkinetic disease and ischemic heart disease. To determine the natural history of these four di