Showing papers by "University of Calgary published in 1988"

Interventive Interviewing: Part III. Intending to Ask Lineal, Circular, Strategic, or Reflexive Questions?

Abstract: Every question asked by a therapist may be seen to embody some intent and to arise from certain assumptions. Many questions are intended to orient the therapist to the client's situation and experiences; others are asked primarily to provoke therapeutic change. Some questions are based on lineal assumptions about the phenomena being addressed; others are based on circular assumptions. The differences among these questions are not trivial. They tend to have dissimilar effects. This article explores these issues and offers a framework for distinguishing four major groups of questions. The framework may be used by therapists to guide their decision making about what kinds of questions to ask, and by researchers to study different interviewing styles.

Measuring depressive symptoms in illness populations: Psychometric properties of the Center for Epidemiologic Studies Depression (CES-D) Scale

Abstract: Psychometric properties of the Center for Epidemiologic Studies Depression (CES-D) scale were examined among five groups that vaned in physical health and illness. Participants included 175 healthy undergraduates, 176 individuals attending family physicians, 107 progressive renal disease, 135 end-stage renal disease, and 120 cancer patients. Individual item and total CES-D scores were relatively symmetrically distributed and varied across the entire range of potentially obtainable scores. Reliability analyses yielded internal consistency (alpha) coefficients ranging from 0.63 to 0.93 across the groups. Test-retest reliability (3-month lag) was 0.61. The CES-D's factorial composition was highly similar to that observed among community volunteers. Varimax-rotated principal-components analyses extracted four factors, corresponding to “depressive affect”, “positive affect”, “somatic and retarded activity”, and “interpersonal”. Moreover, this pattern did not change despite differences in physical heal...

Chemical and isotopic evidence of thermochemical sulphate reduction by light hydrocarbon gases in deep carbonate reservoirs

Abstract: Large H2S accumulations in deep carbonate reservoirs have been attributed to thermochemical sulphate reduction. Although organic matter has been invoked as the reducing agent, individual reactants in specific environments have hitherto not been identified. Carbon isotope data reveal that light hydrocarbon gases have been effective reducing agents in some Palaeozoic foothill reservoirs of western Canada.

Comparison of potassium currents in rabbit atrial and ventricular cells.

Abstract: 1. In rabbit and human hearts there are significant differences in the action potential configuration in atrium and ventricle, and the action potential waveform exhibits marked frequency dependence in both tissues. To study the ionic mechanism(s) of these phenomena, the size and time course of the potassium (K+) currents responsible for repolarization have been recorded from single cells using a whole-cell microelectrode voltage clamp method. 2. At physiological heart rates, the action potential in atrial cells has a short plateau phase; however, the rapid early repolarization is strongly frequency dependent. Ventricular myocytes have a long plateau (400-700 ms at 23 degrees C), and the late repolarizing phase of the action potential is much faster in ventricle than in atrium. 3. In both cell types, four different outward currents can be recorded: (i) a large transient outward current, It; (ii) IK(Ca), a smaller Ca2+-dependent K+ current; (iii) IK, a small, maintained time- and voltage-dependent delayed rectifier K+ current; (iv) IK1, an inwardly rectifying K+ current. 4. It, which is responsible for early repolarization, is much larger in atrium than in ventricle. It has very rapid activation and inactivation kinetics but a very slow time course of recovery from inactivation (tau = 5.4 s at 23 degrees C). Our results show that the reactivation kinetics of It are responsible for the pronounced dependence of the shape of the atrial action potential on stimulus frequency. 5. IK(Ca) is variable from cell to cell and is larger in atrium than in ventricle. In both cell types, IK(Ca) is much smaller than It. 6. The delayed rectifier current, IK, is very small and turns on relatively slowly in both cell types. It is therefore not activated strongly during the relatively short plateau of the atrial action potential. Even in ventricle, it contributes only a small repolarizing current. 7. IK1, the inward rectifier K+ current, is much larger in ventricle than in atrium. The current-voltage relationship for IK1 in ventricle exhibits a negative slope conductance between -50 and 0 mV. IK1 is the outward current which generates the resting membrane potential and it modulates the final repolarization phase of the action potential in both cell types. 8. These data strongly suggest that the action potential configuration and its frequency dependence in rabbit atrial and ventricular cells are mainly due to the differences in sizes and kinetics of It and IK1.

Biological differences between ischemia, hypoglycemia, and epilepsy.

Abstract: Ischemia, hypoglycemia, and epilepsy have long been thought to produce similar or identical brain damage. Furthermore, these insults have been assumed to be additive in their damaging effects. These notions have been based on neuropathological observations in the hippocampus and cerebral cortex, and on the tenet that energy failure (ischemia, hypoglycemia) and increased demand for energy (epilepsy) similarly give rise to selective neuronal necrosis. Recently, other bases for considering these three insults identical have grown out of observations that loss of calcium homeostasis is common to all and that an excitotoxic mechanism of selective neuronal necrosis exists in all three conditions. Fundamental differences between ischemia, hypoglycemia, and epilepsy include the underlying neurochemical changes induced, the neuronal revival times, the time course of neuronal death, the distribution of selective neuronal necrosis, and the likely excitotoxins released. Lactic acid accumulation, implicated in damage to the neuropil as well as to neuronal cell bodies, also occurs to different degrees and in different distributions in the three conditions. The degree and distribution of pannecrosis is thus also different in ischemia, hypoglycemia, and epilepsy.

Competitive inhibition of hsp70 gene expression causes thermosensitivity

Abstract: A novel method has been developed for modulating the expression of an endogenous chromosomal gene in a higher eukaryote, by competitive inhibition at the level of gene transcription. The gene studied was the hsp70 gene, which encodes a 72-kilodalton (kD) heat shock protein that is synthesized after thermal stress. The 59 control region of the hsp70 gene was inserted on a plasmid containing the eukaryotic gene for dihydrofolate reductase. The hybrid plasmid was then introduced into a Chinese hamster ovary cell line and elevated in copy number approximately 20,000-fold by selection of cells with methotrexate. Heat-inducible expression from the intact hsp70 gene was reduced by at least 90% in the modified cells when compared with the induction in control cells, and the modified cells also displayed elevated thermosensitivity. The change in heat shock protein synthesis is presumably caused by competition among the increased number of binding sites for the heat-shock transcription factor, leading to altered expression from the native heat shock gene. These results support a role for heat shock protein in the recovery of mammalian cells from acute thermal stress.

Seasonal range selection in bighorn sheep: conflicts between forage quality, forage quantity, and predator avoidance

Abstract: The migratory and foraging behavior of individually marked bighorn ewes (Ovis canadensis) was studied to test the hypothesis that forage quality determined seasonal range selection. Forage quality was monitored through analysis of fecal crude protein. Ewes in the study population utilized two distinct ranges differing in elevation and possibly predation risk. Pregnant ewes migrated in May from the low-elevation winter range to lambing areas at higher elevation, before plant growth had started there. In so doing, they moved from a range of high-quality forage to one of low-quality forage, apparently to avoid predation on newborn lambs. Non-pregnant adult ewes migrated later. Most yearling ewes (which are not pregnant) migrated with the adult ewes to the lambing areas, but returned to the winter range within a few days, then migrated again to high-elevation areas in June. Forage quality was higher at high elevation from mid-June at least through July, but forage availability appeared to be lower than in the winter range. Seasonal range selection is likely determined by a combination of nutritional and antipredator constraints. The antipredator strategy of bighorn ewes does not always allow them to utilize the range with the best forage.

A kinetic model for the production of liquids from the flash pyrolysis of biomass

Abstract: A kinetically based prediction model for the production of organic liquids from the flash pyrolysis of biomass is proposed. Wood or other biomass is assumed to be decomposed according to two parallel reactions yielding liquid tar and ( gas + char) The tar is then assumed to further react by secondary homogeneous reactions to form mainly gas as a product The model provides a very good agreement with the experimental results obtained using a pilot plant fluidized bed pyrolysis reactor The proposed model is shown to be able to predict the organic liquid yield as a function of the operating parameters of the process, within the optimal conditions for maximizing the tar yields, and the reaction rate constants compare reasonably well with those reported in the literature

Identification and characterization of the human lactoferrin-binding protein from Neisseria meningitidis.

Abstract: Lactoferrin-binding activity in Neisseria meningitidis was detected by a solid-phase binding assay with horseradish peroxidase-conjugated human lactoferrin (HRP-lactoferrin). Expression of lactoferrin-binding activity was regulated by the level of iron in the medium, so that growth in the presence of the iron chelator EDDA (ethylenediamine di-ortho-hydroxyphenylacetic acid) resulted in a greater than 350-fold increase in binding activity, which was reversed by addition of excess iron. A maximal level of expression could be obtained at reasonable culture densities by using either intermediate levels of EDDA or high levels of EDDA and moderate levels of complexed iron sources such as hemoglobin and transferrin. Competition binding assays demonstrated that the binding of lactoferrin was specific for human lactoferrin in that neither bovine lactoferrin, human transferrin, nor human hemoglobin was able to block binding of HRP-lactoferrin. The binding specificity for human lactoferrin correlated with growth studies in which human but not bovine lactoferrin could support the growth of iron-starved cells. Binding of lactoferrin was not dependent on its level of iron saturation, since iron-saturated lactoferrin and apolactoferrin were equally effective at blocking binding of HRP-lactoferrin in competitive binding assays. The lactoferrin-binding protein was identified as a 105,000-molecular-weight iron-regulated outer membrane protein in three different meningococcal strains by a batch affinity method with biotinylated human lactoferrin and streptavidin-agarose.

Identification and characterization of the transferrin receptor from Neisseria meningitidis.

Abstract: Expression of the meningococcal transferrin receptor, detected by assay with human transferrin conjugated to peroxidase, was regulated by the level of iron in the medium. The transferrin receptor was identified by SDS-PAGE and Western blot analysis, as a 71,000 molecular weight iron-regulated outer membrane protein in Neisseria meningitidis B16B6. Growth studies with iron-deficient cells and competition binding experiments demonstrated that the meningococcal receptor was species-specific for human transferrin. Reciprocal competitive binding experiments and limited proteolysis of intact cells indicated that the transferrin and lactoferrin receptors are distinct.

Evidence for initial involvement of macrophage in development of insulitis in NOD mice.

Abstract: Macrophages have been shown to be the major population of infiltrated immunocytes at the early stage of insulitis in diabetes-prone BB rats This study was undertaken to investigate the role of macrophages in the development of insulitis in nonobese diabetic (NOD) mice Administration of cyclophosphamide to NOD mice resulted in a significant increase in the incidence of overt diabetes and severity of insulitis compared with that in untreated NOD mice Intraperitoneal injections of silica completely prevented the development of diabetes and insulitis in both cyclophosphamide-treated and untreated animals Because silica is selectively toxic to macrophages, the results suggest that macrophages play an important role in the initiation of insulitis in NOD mice

Risk of infection after open fracture of the arm or leg.

Abstract: • Two hundred forty consecutive patients admitted for operative treatment of an open fracture of the arm or leg were followed up prospectively for the development of fracture infection. The independent risk of fracture infection was increased in patients with grade IIIB or IIIC fractures, internal or external fixation, lower-leg fracture, any blood transfusion, or injuries resulting from motorcycle accidents or motor vehicle—pedestrian accidents. By stepwise multivariate logistic regression, the most significant risk factors were the grade of the fracture, internal or external fixation, and fractures of the lower leg. These risk factors all represent local wound characteristics, and we conclude that the most important actions by the surgeon to prevent infection involve local wound care. There was no relation between the timing of antibiotic administration or duration of antibiotic therapy and infection risk. (Arch Surg1988;123:1320-1327)

Sequence organization and cytological localization of the minor satellite of mouse

Abstract: A complete 120 bp genomic consensus sequence for the mouse minor satellite has been determined from enriched L929 centromeric sequences. The extensive sequence homology existing between the major and minor satellite suggests an evolutionary relationship. Some sequences flanking the minor satellite has also been identified and they provide insight into centromeric DNA organization. Isotopic in situ hybridization analysis of the minor satellite to mouse L929 and Mus musculus metaphase spreads showed that this repetitive DNA class is localized specifically to centromeres of all chromosomes of the karyotype. With the use of high resolution non-isotopic fluorescence in situ hybridization the minor satellite is further localized to the outer surface of the centromere in a discrete region at or immediately adjacent to the kinetochore. Our cytological data suggests that the minor satellite might play a role in the organization of the kinetochore region rather than, as previously suggested, sites for general anchoring of the genome to the nuclear matrix.

Changes in Cytoskeletal Proteins in the Rat Facial Nucleus Following Axotomy

Abstract: Changes in L-35S-methionine incorporation into cytoskeletal proteins of the facial nucleus of the rat were studied at various times after unilateral crush or resection of the facial nerve by using 2- dimensional gel electrophoresis and fluorography. We found an increase in labeling of actin and tubulin and a decrease in the 68 kDa and 150 kDa neurofilament polypeptides (200 kDa was not studied). The increase in actin and decrease in neurofilament polypeptide labeling was already significant by 24 hr after nerve resection. These changes were more pronounced after nerve resection than after nerve crush on day 7; actin labeling increased to 270%, and tubulin to 205% of contralateral normal nuclei after resection, whereas both proteins increased to only 165% after crush. Neurofilament labeling decreased to 28% of the contralateral side after resection and to 50% after crush. Immunocytochemistry with a monoclonal antibody to the 150 kDa neurofilament component revealed decreased immunoreactivity in the axotomized facial axons at the inner facial genu, 1 cm proximal to the crush. In contrast, neurofilament immunoreactivity was not decreased in the axotomized perikarya of the facial motoneurons. All changes returned to normal 3 weeks after crush. When axonal regeneration was impeded by nerve resection, incorporation into tubulin remained elevated and into neurofilament proteins remained depressed. Actin returned to normal after either nerve resection or crush. We conclude that the synthesis of tubulin and neurofilament proteins following axotomy is regulated by successful axonal regeneration and/or target contact. Actin synthesis seems to be regulated independently of target- derived factors.

Parallel stranded DNA

Abstract: A series of four hairpin deoxyoligonucleotides was synthesized with a four-nucleotide central loop (either C or G) flanked by the complementary sequences d(T)10 and d(A)10. Two of the molecules contain either a 3'-p-3' or 5'-p-5' linkage in the loop, so that the strands in the stem have the same, that is, parallel (ps) polarity. The pair of reference oligonucleotides have normal phosphodiester linkages throughout and antiparallel (aps) stem regions. All the molecules adopt a duplex helical structure in that (i) the electrophoretic mobilities in polyacrylamide gels of the ps and aps oligomers are similar. (ii) The ps hairpins are substrates for T4 polynucleotide kinase, T4 DNA ligase, and Escherichia coli exonuclease III. (iii) Salt-dependent thermal transitions are observed for all hairpins, but the ps molecules denature 10 degrees C lower than the corresponding aps oligomers. (iv) The ultraviolet absorption and circular dichroism spectra are indicative of a base-paired duplex in the stems of the ps hairpins but differ systematically from those of the aps counterparts. (v) The bis-benzimidazole drug Hoechst-33258, which binds in the minor groove of B-DNA, exhibits very little fluorescence in the presence of the ps hairpins but a normal, enhanced emission with the aps oligonucleotides. In contrast, the intercalator ethidium bromide forms a strongly fluorescent complex with all hairpins, the intensity of which is even higher for the ps species. (vi) The pattern of chemical methylation is the same for both the ps and aps hairpins. The combined results are consistent with the prediction from force field analysis of a parallel stranded right-handed helical form of d(A)n.d(T)n with a secondary structure involving reverse Watson-Crick base pairs and a stability not significantly different from that of the B-DNA double helix. Models of the various hairpins optimized with force field calculations are described.

Visual Changes in Daily Life Throughout Adulthood

Abstract: A pair of surveys asked healthy adults about their everyday visual problems. Participants ranged in age from 18 to 100 and were screened for major visual impairment. Respondents rated the frequency of difficulty they had performing visual tasks such as reading, recognizing objects, picking out a face in a crowd, seeing in dimly lit environments, seeing moving objects, and so on. The surveys revealed five dimensions that declined with increasing age: visual processing speed, light sensitivity, dynamic vision, near vision, and visual search. The percentage of respondents reporting a decline in these visual dimensions increased two- to sixfold across the adult life span. Varying rates of visual decline for different tasks suggest that various aspects of vision age at different rates.

Analysis of an algorithm for fast ray tracing using uniform space subdivision

Abstract: Ray tracing is becoming popular as the best method of rendering high quality images from three dimensional models. Unfortunately, the computational cost is high. Recently, a number of authors have reported on ways to speed up this process by means of space subdivision which is used to minimize the number of intersection calculations. We describe such an algorithm together with an analysis of the factors which affect its performance. The critical operation of skipping an empty space subdivision can be done very quickly, using only integer addition and comparison. A theoretical analysis of the algorithm is developed. It shows how the space and time requirements vary with the number of objects in the scene.

Increased glial fibrillary acidic protein synthesis in astrocytes during retrograde reaction of the rat facial nucleus.

Abstract: Glial fibrillary acidic protein (GFAP) increases in astrocytes following axotomy of facial motoneurons. In the present study we quantified GFAP synthesis both in regenerating facial nuclei after nerve crush and in nonregenerating facial nuclei after nerve resection. An increase in GFAP synthesis during regeneration occurs as early as 24 h after the axotomy. Thus, the increase in the astrocytic GFAP synthesis seems to be the earliest glial response to retrograde changes in facial motoneurons.

Birthdate and survival in bighorn lambs (Ovis canadensis)

Abstract: The relationship between parturition date and lamb survival was investigated among individually marked bighorn ewes in south-western Alberta, Canada. Lambs were born from 17 May to 21 July. Most births occurred in the first two weeks of the lambing period. Lambs born in May enjoyed greater survival than lambs born in June and July. The viability of lambs born after 10 June was extremely low. Inadequate nutrition is suggested as the cause of greater mortality of lateborn lambs. Ewes that give birth late are at an earlier stage of lactation when forage quality declines and may not produce sufficient milk to ensure lamb survival. Their lambs have access to high-quality forage for a shortened period. The proportion of late lambs appeared to be correlated with ewe density in the winter range.

Sequential thallium-201 myocardial perfusion studies after successful percutaneous transluminal coronary artery angioplasty: delayed resolution of exercise-induced scintigraphic abnormalities.

Abstract: To characterize the sequential changes of myocardial perfusion scintigraphy in patients with coronary artery disease (CAD) after complete revascularization, 43 patients underwent exercise thallium-201 (201Tl) myocardial perfusion scintigraphy before and at 9 +/- 5 days, 3.3 +/- 0.6, and 6.8 +/- 1.2 months after percutaneous transluminal coronary angioplasty (PTCA). Only patients with single-vessel CAD, without previous myocardial infarction, and without evidence of restenosis at 6 to 9 months after PTCA were included. Perfusion scans were analyzed blindly with the use of a new quantitative method to define regional myocardial perfusion in the topographic distribution of each coronary artery, which was shown to be reproducible (r = .94 or higher and SEE of 7% or less, between repeated measures by one and two operators). At 4 to 18 days after PTCA, the mean treadmill walking time increased by 123 +/- 42 sec, mean exercise-induced ST segment depression decreased by 0.6 +/- 0.3 mm, group maximal heart rate increased by 20 +/- 9 beats/min, and group systolic blood pressure at peak exercise increased by 24 +/- 10 mm Hg, compared with pre-PTCA values (p less than .001). However, no group differences were noted in these variables between the three post-PTCA stages. Myocardial perfusion in the distribution of the affected (dilated) coronary artery, on the other hand, improved progressively. In the 45 degree left anterior oblique view for instance, myocardial perfusion increased at 9 days after PTCA (from 68 +/- 24% before PTCA to 91 +/- 9%, p less than .001) and at 3.3 months after PTCA (101 +/- 8%, p less than .05 vs 9 days after PTCA), but no further significant changes were seen at 6.8 months after PTCA (102 +/- 8%). Similar changes were noted in the other two views. No relationship between minor complications during PTCA and delayed improvement on the 201Tl was observed. Myocardial ischemia was diagnosed in 12 of the 43 scans recorded a few days after PTCA, but in none recorded at later stages. We conclude that 201Tl scans after PTCA often show delayed improvement and therefore, an abnormal myocardial perfusion scan soon after PTCA does not necessarily reflect residual coronary stenosis or recurrence.

Neuropeptide Y action in the rat hippocampal slice: site and mechanism of presynaptic inhibition

Abstract: Neuropeptide Y (NPY), the most abundant peptide in mammalian CNS, has been shown to inhibit excitatory neurotransmission presynaptically at the stratum radiatum-CA1 synapse in the in vitro rat hippocampal slice. We examined the site and mechanism of this inhibition in a series of in vitro intra- and extracellular recordings in areas CA1 and CA3, the source of much of the excitatory synaptic input to the CA1 neurons. NPY's inhibitory action at the stratum radiatum-CA1 synapse was unaffected by high concentrations of the antagonists bicuculline, theophylline, or atropine, suggesting that it does not act by stimulating the release of the known presynaptic inhibitory transmitters GABA, adenosine, or ACh, respectively. Bath application of 10(-6) NPY, a concentration that strongly inhibited the stratum radiatum-CA1 synapse had no effect on CA3 neuron resting potential, input resistance or action potential amplitude, threshold, or duration. NPY also does not alter the amplitude or duration of the prolonged CA3 action potentials evoked in the presence of TTX, tetraethyl-ammonium, and elevated external Ca2+ or those evoked in the presence of TTX and Ba2+ ions. NPY therefore does not alter the passive or active properties of the somata of the presynaptic CA3 neurons. Neither the afferent fiber volley of the Schaffer collaterals in stratum radiatum of area CA1 nor the excitability of the CA3 terminals in CA1 was affected by NPY application. However, application of the transient K+ current blocker, 4-aminopyridine (4-AP) at concentrations of 10 and 50 microM, completely abolished the action of 10(-6) M NPY on the stratum radiatum-CA1 excitatory synaptic potentials. This action of 4-AP could be reversed by reducing extracellular Ca2+ concentrations from a control level of 1.5 to 0.7 mM (in 10 microM 4-AP) and to 0.5 mM (in 50 microM 4-AP). The evidence suggests that NPY inhibits excitatory synaptic transmission at the Schaffer collateral-CA1 synapse by acting directly at the terminal to reduce a Ca2+ influx.