Showing papers by "University of Victoria published in 1991"

Purification and characterization of thin, aggregative fimbriae from Salmonella enteritidis.

Abstract: Novel fimbriae were isolated and purified from the human enteropathogen Salmonella enteritidis 27655. These fimbriae were thin (measuring 3 to 4 nm in diameter), were extremely aggregative, and remained cell associated despite attempts to separate them from blended cells by centrifugation. The thin fimbriae were not solubilized in 5 M NaOH or in boiling 0.5% deoxycholate, 8 M urea, or 1 to 2% sodium dodecyl sulfate (SDS) with or without 5% beta-mercaptoethanol. Therefore, an unconventional purification procedure based on the removal of contaminating cell macromolecules in sonicated cell extracts by enzymatic digestion and preparative SDS-polyacrylamide gel electrophoresis (PAGE) was used. The insoluble fimbriae recovered from the well of the gel required depolymerization in formic acid prior to analysis by SDS-PAGE. Acid depolymerization revealed that the fimbriae were composed of fimbrin subunits, each with an apparent molecular mass of 17 kDa. Although their biochemical characteristics and amino acid composition were typical of fimbriae in general, these thin fimbriae were clearly distinct from other previously characterized fimbriae. Moreover, their fimbrin subunits had a unique N-terminal amino acid sequence. Native fimbriae on whole cells were specifically labeled with immune serum raised to the purified fimbriae. This immune serum also reacted with the denatured 17-kDa fimbrin protein in Western blots. The polyclonal immune serum did not cross-react with the other two native fimbrial types produced by this strain or with their respective fimbrins on Western blots (immunoblots). Therefore, these fimbriae represent the third fimbrial type produced by the enteropathogen S. enteritidis. Images

Some epidemiological models with nonlinear incidence

Abstract: Epidemiological models with nonlinear incidence rates can have very different dynamic behaviors than those with the usual bilinear incidence rate. The first model considered here includes vital dynamics and a disease process where susceptibles become exposed, then infectious, then removed with temporary immunity and then susceptible again. When the equilibria and stability are investigated, it is found that multiple equilibria exist for some parameter values and periodic solutions can arise by Hopf bifurcation from the larger endemic equilibrium. Many results analogous to those in the first model are obtained for the second model which has a delay in the removed class but no exposed class.

Growth of Francisella spp. in rodent macrophages.

Abstract: We examined the nature of the interactions between the facultative intracellular pathogens Francisella tularensis and F. novicida and rodent macrophages. Growth of F. tularensis LVS was observed in macrophage monolayers from mice, guinea pigs, or rats. In contrast, F. novicida grew in macrophages from mice and guinea pigs but not in macrophages from rats. Transmission electron microscopy studies indicated that both Francisella species survive within macrophage phagosomes that are unfused with lysosomes. Images

Traditional Plant Foods of Canadian Indigenous Peoples: Nutrition, Botany and Use

Abstract: First published in 1991, Traditional Plant Foods of Canadian Indigenous Peoples details the nutritional properties, botanical characteristics and ethnic uses of a wide variety of traditional plant foods used by the Indigenous Peoples of Canada. Comprehensive and detailed, this volume explores both the technical use of plants and their cultural connections. It will be of interest to scholars from a variety of backgrounds, including Indigenous Peoples with their specific cultural worldviews; nutritionists and other health professionals who work with Indigenous Peoples and other rural people; other biologists, ethnologists, and organizations that address understanding of the resources of the natural world; and academic audiences from a variety of disciplines.

How States Utilize Foreign Evidence

Abstract: This article examines how evidence about Program A in Country A may be utilized in Country B, and thus how utilization may explain the adoption of the same program. Elites and activists have a number of interests in using policy evidence from another country: to put an issue to a systemic or institutional agenda, mollify political pressure, provide an exemplar, indicate the range of options or reinforce conclusions already reached. The interests of the importer dictate the nature, timing and origins of the evidence injected into policy debate. This framework is applied to the case of freedom of information policy. An analysis of how and why evidence about the United States Freedom of Information Act (FOIA) was utilized in Canada and Britain reveals that FOIA was used as an exemplar in Canada and the reverse in Britain.

Families of Young Children with Handicaps: Parental Stress and Family Functioning.

Abstract: The association of the presence of a child with handicaps and parental stress and family dysfunctioning was examined Fifty-five families with young children with handicaps were compared with a matched group of families of children without handicaps on the variables of parental stress and family functioning Results of family psychological measures suggest that families may be resilient in adapting to the demands of raising a child with handicaps Although families of such children appeared to have high degrees of stress, they differed only minimally from other families in their family functioning These results reinforce the need for family intervention to alleviate parental stress and for individualized programs emphasizing family strengths and idiosyncratic attributes

Identification, characterization, and spatial localization of two flagellin species in Helicobacter pylori flagella.

Abstract: Flagellar filaments were isolated from Helicobacter pylori by shearing, and flagellar proteins were further purified by a variety of techniques, including CsCl density gradient ultracentrifugation, pH 2.0 acid disassociation-neutral pH reassociation, and differential ultracentrifugation followed by molecular sieving with a Sephacryl S-500 column or Mono Q anion-exchange column, and purified to homogeneity by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transfer to an Immobilon membrane. Two flagellin species of pI 5.2 and with apparent subunit molecular weights (Mrs) of 57,000 and 56,000 were obtained. N-terminal amino acid analysis showed that the two H. pylori flagellin species were related to each other and shared sequence similarity with the N-terminal amino acid sequence of Campylobacter coli, Bacillus, Salmonella, and Caulobacter flagellins. Analysis of the amino acid composition of the predominant 56,000-Mr flagellin species isolated from two strains showed that it was comparable to the flagellins of other species. The minor 57,000-Mr flagellin species contained a higher content of proline. Immunoelectron microscopic studies with polyclonal monospecific H. pylori antiflagellin antiserum and monoclonal antibody (MAb) 72c showed that the two different-Mr flagellin species were located in different regions of the assembled flagellar filament. The minor 57,000-Mr species was located proximal to the hook, and the major 56,000-Mr flagellin composed the remainder of the filament. Western immunoblot analysis with polyclonal rabbit antisera raised against H. pylori or Campylobacter jejuni flagellins and MAb 72c showed that the 56,000-Mr flagellin carried sequences antigenetically cross-reactive with the 57,000-Mr H. pylori flagellin and the flagellins of Campylobacter species. This antigenic cross-reactivity did not extend to the flagellins of other gram-negative bacteria. The 56,000-Mr flagellin also carried H. pylori-specific sequences recognized by two additional MAbs. The epitopes for these MAbs were not surface exposed on the assembled inner flagellar filament of H. pylori but were readily detected by immunodot blot assay of sodium dodecyl sulfate-lysed cells of H. pylori, suggesting that this serological test could be a useful addition to those currently employed in the rapid identification of this important pathogen.

Adult age differences in direct and indirect tests of memory.

Abstract: Indirect tests of memory assess the influence of recent experience on task performance without requiring awareness of remembering. Evidence concerning whether there are reliable age differences on such indicators of implicit memory has been inconsistent. This inconsistency may be related either to the low power of previous studies, or the contamination of indirect measures by conscious memory retrieval strategies. In a statistically powerful test of this question, indirect and direct tests of memory were administered to 584 adults from three age groups (19-36 years, 55-69 years, 70-86 years). Significant age differences in favor of the young were found on the indirect test as well as direct tests, suggesting that there are small but reliable age differences in implicit memory. Correlational analyses examining the relationship of memory performance to other cognitive variables indicated that the indirect test was supported by different components than the direct tests.

The relationship between self-efficacy and depression in adolescents.

Abstract: This study examined the self-efficacy status of depressed versus nondepressed adolescents. As predicted, self-efficacy was negatively correlated with depression. A three-way interaction of Sex x Age x Level of Depression suggested separate analyses for males and females. Regression analysis revealed age-related changes in the dependence of depression scores on general, academic, physical and social self-efficacy status. It was concluded that self-efficacy has an important relationship with adolescent depression. The implications of these findings are discussed.

Secondary science teachers' attitudes toward and beliefs about science reading and science textbooks

Abstract: Science textbooks are dominant influences behind most secondary science instruction but little is known about teachers' approach to science reading. The purpose of this naturalistic study was to develop and validate a Science and Reading Questionnaire to assess secondary science teachers' attitudes toward science reading and their beliefs or informed opinions about science reading. A survey of 428 British Columbia secondary science teachers was conducted and 215 science teachers responded. Results on a 12-item Likert attitude scale indicated that teachers place high value on reading as an important strategy to promote learning in science and that they generally accept responsibility for teaching content reading skills to science students. Results on a 13-item Likert belief scale indicated that science teachers generally reject the text-driven model of reading, but they usually do not have well-formulated alternative models to guide their teaching practices. Teachers have intuitive beliefs about science reading that partially agree with many research findings, but their beliefs are fragmented and particularly sketchy in regard to the cognitive and metacognitive skills required by readers to learn from science texts. The findings for attitude, belief, and total scales were substantiated by further questions in the Science and Reading Questionnaire regarding classroom practice and by individual interviews and classroom observations of a 15-teacher subsample of the questionnaire respondents.

Homelessness: A Criminogenic Situation?

Abstract: Criminologists have been reluctant to pursue the idea that situational factors encourage criminal activity. Following Gibbons's work on criminogenic situations', we investigate the criminogenic' nature of homelessness. Using data on a sample of homeless youth (N = 390) in Toronto, Canada, we find that a significantly greater proportion of these young people commits offences after, rather than before, leaving home. Moreover, this pattern does not appear to be an effect of age, gender, or the number of previous homeless experiences; instead, it appears to be a result of the current homeless situation.

Initial light curve of Q2237 + 0305

Abstract: This paper presents CCD photometry for the gravitationally lensed quasar system 2237 + 0305, in optical passbands from B through R, taken over a time period of more than 3 yr. These data provide new information about the probable microlensing event reported by Irwin et al. (1989); the rise time of this feature is approximately 26 days. Four additional independent brightness changes in the quasar images are detected.

High-affinity binding of the basement membrane proteins collagen type IV and laminin to the gastric pathogen Helicobacter pylori.

Abstract: The ability of 16 isolates of the human gastroduodenal pathogen Helicobacter pylori to bind 125I-radiolabelled tissue proteins was quantitated by liquid-phase assay. While capable of binding generally low levels of collagen types I and II, vitronectin, and fibronectin (average binding, 8%; highest binding, 23%), the various H. pylori isolates were good binders of the basement membrane proteins collagen type IV and laminin (average binding, 27%; highest binding, 60%). Campylobacter species tested bound lower levels of collagen type IV and laminin (average binding, 12%; highest binding, 17%). Trypsin and proteinase K treatment of H. pylori cells markedly reduced the binding of collagen type IV and laminin, as did heat treatment, suggesting that the binding of basement membrane proteins is mediated by bacterial surface proteins. Binding of both basement membrane proteins was rapid and saturable. 125I-collagen type IV binding to H. pylori 915 was inhibited by preincubation with unlabelled collagen type IV but was not inhibited by laminin or a number of other proteins. Once bound, radiolabelled collagen type IV but was not displaced by an excess of unlabelled collagen type IV, indicating that the binding interaction was of high affinity. Binding of laminin was partially reversible, and analysis in a solid-phase nonradiolabel assay showed that the interaction was of high affinity, with a Kd of 7.9 nM. This interaction was affected by salt, indicating the presence of a hydrophobic component in the ability of H. pylori to bind laminin.

Carbonate deposits in marine fish intestines: A new source of biomineralization

Abstract: Marine teleostean fish are hypo-osmotic to seawater. As part of a multiorgan osmoregulatory strategy they drink seawater and selectively absorb water and minerals across the intestinal epithelium. Notably, divalent cations (Ca2+ and MgZ’) are left behind. We report here that in the gulf toadfish, Opsanus beta, the ionic by-products of osmoregulation in the intestine contribute to de novo formation of a carbonate mineral, tentatively identified as calcian kutnohorite. Our data suggest that intestinal mineralization is a general feature of osmoregulation in marine teleosts and that this process is an unrecognized and possibly substantial source of marine carbonate sediments. Acknowledgments We are grateful to Terry Nelsen for performing the X-ray diffraction measurements, to Nidia Romer for technical assistance, to Jose Lea1 and Don Heuer for photographic assistance, and to Jimbo Luznar for providing the toadfish. We thank C. M. Wood and W. Balch for commenting on an earlier draft of this paper. This research was supported by grants from NSF and NIH (P.J.W.) and the Natural Sciences and Engineering Research Council of Canada (T.P.M.). Fish actively recycle and transport marine carbonate sediments through ingesting, pulverizing, and excreting calcified food organisms such as corals, coralline algae, or molluscs (Barnes 1983). While investigating fates of urea C (Mommsen and Walsh 1989) in the gulf toadfish (Opsanus beta) we observed soft, white pellets in the intestine and feces. These pellets effervesced upon HCl addition. The striking uniformity of the pellets and the fact that they were found in starved fish led us to suspect that they were not of dietary origin. We considered two other possible origins of this material in the design of the present study. First, our previous hypothesis on the existence of urea recycling through microbial urease (urea + NH, and CO,) in the toadfish intestine (Mommsen and Walsh 1989) suggested that urease-enhanced rates of CO2 production and NH, buffering might contribute to mineralization. Second, the well-documented Rg. 1. Carbonate depua~~a m toadfish intcarmc. A. Fresh mtcstmc disseaed IO rcvcal numerous carbonate pellets(p). Anterior(oral) cndlsat right. Scale bar-20 mm B. Scanningelectron micrograph ofapelletcontalnmg carbonate crystal aggregates. The pellets are covered with a membrane (m) and are rich in bacterialike rods (b). Energy drspersive spectroscopy indicated that the mmeral grains arc rich in Ca and Mg and low in Mn. Scale bar-40 WI C. Transmission electron micrograph ofa scclion through the tissue adjacent to the crystal aggregates vatbin the intestine. Note the closely associated mitochondria (ml) and the relationshIps between the rice-grainshaped crystal aggrega~s (c) and layer of organic material between the tissue and crystal aggregates. Scale bar2 pm. D. Transmission electron mrcrograph of the crystal aggregates withm the intestme lumen. Most 01 the cryslal aggregates arc in cross sectmn and the center of each conlams a void area (v) and an organic matrix material (ma) which may act as a site for crystal nucleatmn. Scale bar-O.5 pm. hydrommeral transport capabuues of teleostean intestinal tissues suggested an alternative source of CO, (respiration) as well as potential concentrating mechanisms for organic ions (Presser 1973; Howe and Gutknecht 1978; Schmidt-Nielsen 1983; Groat and Bakker 1988). We report that the pellets consist of a relatively unusual carbonate mineral tentatively identified as calcian kutnohorite. This mineral is formed de now in the toadfish intestine and excreted even in the absence of any dietary input. Our experiments suggest that this heretofore unrecognized mode ofbiomineralization does not intimately invalve mtesrmal microbes, but IS a by-product of routine osmoregulation by this species. Our model suggests that this process is a potentially significant source of carbonate mineral in the marine environment. Toadfish (S-500 g) were maintained in seawater aquaria without access to food, gravel, air-stones, or other foreign substances for a minimum of 3 weeks, unless noted. Regardless of sex or size, intestines of all toadfish contained substantial numbers of pellets (Fig. 1A; Table 1) identical to those first observed in freshly caught specimens and contained no other visible particulate materials. Although calcified or-

Type 1 fimbriae of Salmonella enteritidis.

Abstract: Salmonella enteritidis was previously shown to produce fimbriae composed of 14,000-molecular-weight (Mr) fimbrin monomers (J. Feutrier, W. W. Kay, and T. J. Trust, J. Bacteriol. 168:221-227, 1986). Another distinct fimbrial structure, comprising 21,000-Mr fimbrin monomers, has now been identified. These fimbriae are simply designated as SEF 14 and SEF 21, respectively (for S. enteritidis fimbriae and the Mr [in thousands] of the fimbrin monomer). A simple method for the purification of both structures was developed by using the different biochemical properties of these fimbriae. SEF 21 remained intact after being boiled in sodium dodecyl sulfate but readily dissociated into subunits of 21,000 Mr at pH 2.2. The overall amino acid composition and the N-terminal amino acid sequence of the SEF 21 fimbrin were distinct from those of SEF 14 but were virtually identical to the predicted sequence for type 1 fimbrin of Salmonella typhimurium. Immunoelectron microscopy of S. enteritidis clearly revealed fimbrial structures that reacted with immune serum specific to the 21,000-Mr fimbrin. Immune sera raised against this subunit were cross-reactive with type 1 fimbrins found in whole-cell lysates of S. typhimurium, Salmonella illinois, and Salmonella cubana. However, there was no cross-reaction with Escherichia coli type 1 fimbriae or with other fimbrins produced by S. enteritidis. Under certain growth conditions, S. enteritidis produced both SEF 14 and SEF 21. However, when S. enteritidis was grown at 30 degrees C or lower, only the 21,000-Mr SEF 21 fimbrin could be detected. There was a direct correlation between mannose-sensitive hemagglutination and the presence of SEF 21.

Diazepam impairs acquisition but not performance in the Morris water maze.

Abstract: Diazepam is known to produce anterograde amnesia in both humans and animals. The present investigation sought to determine if this impairment is a direct result of diazepam's interference with mnemonic processes or a result of deficits in performance or retrieval. Diazepam (3 mg/kg) was administered prior to training in the Morris water maze either before or after the rats had acquired the location of a submerged escape platform. Diazepam was found to impair acquisition but not retrieval of spatial information and this impairment was not due to the sedative, hypothermic or state-dependent learning effects of diazepam. These results replicate previous findings in the Morris water maze and provide new evidence that this deficit is primarily mnemonic in nature.

Fear Appeals, Individual Differences, and Environmental Concern

Abstract: In this study, the authors examined the effect of a brief but intense antipollution message on verbal commitment (stated willingness to act) and on three forms of immediate behavioral commitment (donating money, donating time, and signing a petition). Exposure to the antipollution message produced significantly more verbal commitment and financial donations but not more time donations than did exposure to a control message. Nearly every participant signed the petition. To determine whether environmental fear appeals should be targeted at specific audiences, the authors computed correlations between seven individual difference variables and environmental concern. None of the individual difference variables were significantly related to financial or time donations. However, political orientation was significantly correlated with verbal commitment.

International economic structures, government interests, and international coordination of macroeconomic adjustment policies

Abstract: Analysts have commonly argued that there has been a decline in international coordination of the kinds of policies that governments can use to manage the international payments imbalances that emerge when different governments pursue different macroeconomic policies. The decline typically has been attributed to a posited decline in American hegemony. In contrast, this article argues that international coordination of macroeconomic adjustment policies (trade and capital controls, exchange rate policies, balance-of-payments financing, and monetary and fiscal policies) was at least as extensive for much of the 1980s as it had been in the 1960s. There was, however, a shift away from coordination of balance-of-payments financing and other policies that have limited direct consequences for domestic economic and political conditions and a concurrent shift toward coordination of monetary and fiscal policies that are critically important for domestic politics and economics. This change is best explained as a consequence of changes in the structure of the international economy. Most important, international capital market integration encouraged governments to coordinate monetary and fiscal policies because balance-of-payments financing and exchange rate coordination alone are insufficient to manage the enormous payments imbalances that emerge when capital is able to flow internationally in search of higher interest rates and appreciating currencies.

Paper Versus Polystyrene: A Complex Choice

Abstract: As today's public and governments become more environmentally conscious we are increasingly concerned about the environmental component of product and service options available in our affluent society. Our choices are often made instinctively, from necessity, since a detailed analysis of the relative environmental merits of using canned versus fresh versus frozen foods, or glass versus paper versus steel versus aluminum packaging would simply be too time consuming for each purchase. If, however, the environmental merit question is restricted to a small enough purchase sector it is possible to conduct a complete analysis of relative merit from the initial resource through the manufacturing stages, use attributes, and recycle options through to final use or disposal of the item. Many environmentally appropriate choices of products can only be made after such an analysis. An outline of one such analysis, that of paper versus polystyrene foam as the material of construction for hot drink containers in fast food or other single use applications, is given here.

The Leishmania donovani lipophosphoglycan T lymphocyte-reactive component is a tightly associated protein complex.

Abstract: Lymphocytes from mice immunized with Leishmania donovani (LPG) were specifically stimulated to proliferate in vitro by purified LPG or its delipidated congener, phosphoglycan. The response was dose dependent and required prior immunization with either LPG or phosphoglycan. Proliferation was eliminated by specific depletion of Thy-1+ cells with antisera and C and the proliferating T cell subset was shown to be CD4+CD8-. Tests of various LPG fragments indicated that the T cell stimulation was associated with the core structure of LPG rather than the lipid or phosphoglycan repeat structure. However, amino acid analysis of LPG and active LPG fragments, after acid hydrolysis, showed the presence of amino acids in peptide linkage. Specific hydrolysis of the glycosidic linkages in LPG with trifluoromethanesulfonic acid provided polypeptide material reactive with two mAb previously believed to be LPG carbohydrate core specific. The protein was separated from LPG by reverse phase chromatography and shown to be a complex of proteins with common epitopes recognized by the two mAb. The dominant species isolated from LPG was a set of small, approximately 11,000 Mr, molecules. Subsequent T cell proliferation studies showed that the lymphocyte stimulation was associated with the protein component of LPG and not the glycan.

Elementary school teachers' beliefs about and perceptions of elementary school science, science reading, science textbooks, and supportive instructional factors

Abstract: This article is a report of elementary school teachers' beliefs about and uses of text material in science. Survey results from 522 K-8 teachers from 299 schools in the United States, Puerto Rico and the Virgin Islands were analyzed along three dimensions: teacher attitudes toward teaching of reading in science; teacher beliefs and understanding about models of reading, factors influencing science reading and reading skills; and teacher use of various teaching strategies. Results suggest that teachers do not see reading science as different from any other narrative material. And though most agreed to the importance of having students do activities to support and enhance the use of text material, responses suggest that covering topics is still a concern for most elementary teachers.

The Autocorrelation of Hourly Wind Speed Observations

Abstract: The autocorrelation of hourly wind speed observations is estimated for seven stations on the west coast of Canada at selected lags ranging from one hour to two months. The estimated autocorrelation function is fitted by a model that includes a modified exponential term and cosine terms. The autocorrelation function declined more slowly than a simple exponential at six of the seven stations. For lags up to 12 hours autocorrelation coefficients were highest at those stations with the most uniform surrounding topography. The autocorrelation functions did not attenuate to zero at lags up to two months. An assumption of independent observations would underestimate standard errors of series statistics.

Pedigrees of neurobehavioral circuits: tracing the evolution of novel behaviors by comparing motor patterns, muscles, and neurons in members of related taxa.

Abstract: Comparisons of homologous elements in neurobehavioral circuits that have diverged during speciation to mediate different behaviors should reveal the nature of evolutionary changes in nervous systems.

Uniformly-most reliable networks do not always exist

Abstract: Boesch conjectured that there is always a uniformly-most reliable graph on n points and e edges. We present an infinite family of counterexamples to this conjecture.