Showing papers by "University of Manitoba published in 1982"

Application of thyroid and steroid hormones as anabolic agents in fish culture

Abstract: A basic premise in any intensive culture system is to maximize growth at minimum cost, with an end product that is of high nutritive value and aesthetically acceptable to the consumer. This review is directed towards evaluating the role for thyroid hormones and steroids in fish culture. Particular attention has been given to the following topics: growth, appetite, food conversion, carcass composition, salt water tolerance, species specificity, deleterious responses and economic implications.

Calcium movements in relation to heart function.

Abstract: It is widely recognized that calcium is of singular importance in the viability of the myocardial cell, nonetheless little is known concerning the precise nature of the action of calcium in myocardium as to how it maintains the life of the cell and how it may dictate the death of the cell. However, recent advances in research involved with the study of calcium movement in the heart have been highly valuable for the formulation of new concepts with respect to the physiological and pathological aspects of calcium metabolism in the myocardium. It is becoming clear that calcium movements are closely related to cardiac electrophysiological events, contractile function, membrane integrity and energy metabolism. In particular, a novel theory involving phosphatidylinositol turnover and Ca2+-dependent ATPase activation has been advanced regarding the mechanism and control of calcium entry into the cardiac cell upon excitation. Alterations in the regulation of calcium metabolism through the interaction of a number of separate, elements may affect calcium distribution in the cell and thereby may change cardiac function and metabolism. The part calcium plays in the genesis of pathological states in the myocardium is discussed in the light of research employing various experimental protocols. Intracellular calcium overload and deficiency are postulated to contribute to cardiac contractile failure and cell death through a number of distinct mechanisms. It is now a real challenge to understand the precise nature of processes associated with the occurrence of intracellular calcium overload or intracellular calcium deficiency in order to achieve proper management of cardiac disorders.

On the annular‐to‐wavy flow pattern transition during condensation inside horizontal tubes

Abstract: The annular to wavy and intermittent flow pattern transition during condensation inside horizontal tubes was investigated. Eight data sets corresponding to different tube diameters and different test fluids were used to test the predictions of several diabatic and adiabatic correlations. Deficiencies were found in these correlations which prevented consistent agreement with the data base. An improved correlation is proposed and shown to have a good deal of generality and accuracy in predicting this transition. On a etudie le passage du regime d'ecoulement annulaire au regime ondulatoire et intermittent, lors de la condensation a l'interieur des tubes horizontaux. On a employe huit series de donnees, qui correspondaient a differents diametres de tubes et divers fluides d'essai, pour verifier les previsions de diverses correlations diabatiques et adiabatiques. On a trouve des deficiences dans ces correlations, de sorte que l'on n'a pu obtenir un accord satisfaisant pour l'ensemble de ces donnees; on propose une meilleure correlation dont on montre qu'elle possede beaucoup de generalite et d'exactitude pour la prediction de cette transition.

Cardiac alpha- and beta-adrenergic receptor alterations in diabetic cardiomyopathy

Abstract: The effect of chronic experimental diabetes on the adrenergic receptors in the rat heart was investigated. Diabetes was induced by streptozotocin (65 mg/kg; i.v.) administration, animals were sacrificed 8 weeks later, and positive as well as negative dF/dt values were determined in isolated papillary muscle preparations. Stimulation of the contractile force generation by isoproterenol and methoxamine was attenuated in diabetic preparations. Beta-and alpha-adrenergic receptor bindings were determined in cardiac membranes by employing3H-dihydroalprenolol and3H-dihydroergocryptine respectively. Reduced number of beta- and alpha-receptor binding sites without changes in the affinity constants were observed in diabetic myocardium. Such a decrease in alpha- and beta-receptor density in the heart may account for the depressed contractile responsiveness to adrenergic stimuli in diabetic cardiomyopathy.

The Association of Urinary Tract Infection with Sexual Intercourse

Abstract: To assess the significance of sexual intercourse as a precipitating factor of urinary tract infection in premenopausal women with recurrent infection, 15 patients were monitored with daily dipslides and calendar recording of intercourse episodes after antimicrobial prophylaxis was discontinued. Eleven patients experienced 16 infections; 12 infections occurred within 24 hr of an intercourse episode, two occurred during the menstrual period, and two had no recognizable association. In 12 control subjects, followed in a similar fashion, three infections--all within 24 hr of an intercourse episode--were documented. There was no difference in frequency of intercourse between patients and controls, but the frequency was higher in infected women than in uninfected women (P less than 0.02). These data suggest that in sexually active women, most urinary tract infections are intercourse-related.

Characterization of the Two Forms of Rat Placental Lactogen (rPL): rPL-I and rPL-II*

Abstract: Two forms of rat placental lactogen are secreted during pregnancy. The time of appearance during gestation and the concentration of each form are different. The two forms also differ in half-time disappearance rate from the circulation, molecular weight, electrophoretic mobility, and immunoreactivity.

Adolescent marijuana use: a review.

Abstract: The adolescent marijuana literature is reviewed. Studies show that the prevalence of marijuana use is generally quite low in elementary schools. In junior and senior high samples, findings vary greatly from place to place. The prevalence of use increased dramatically during the 1970s although the use patterns may have peaked already in some areas. The use of marijuana increases with age, but some evidence suggests that a slight drop-off in use occurs near the end of high school. Female use seems to be increasing more than male use. Use seems to be somewhat more prevalent in middle- and upper-middle-class homes and in broken homes. Mixed support has been found for the hypothesis that marijuana users have parents that are more permissive. Parents of marijuana users are generally characterized as being less warm and supportive, and more inclined toward the use of drugs themselves. Peer and sibling use of marijuana seem to be particularly important predictors of adolescent marijuana use. Findings on personali...

Fatty acid activation and temperature perturbation of rat brain microsomal phospholipase D.

Abstract: The hydrolytic and transphosphatidylation activities of rat brain microsomal phospholipase D were highly latent in the absence of an appropriate activator. The most suitable surfactants for this activation were oleate and palmitoleate. Besides the bile acids and unsaturated fatty acids, other naturally occurring surfactants, such as lysophospholipids, acidic phospholipids, acyl-CoA's, and gangliosides, were inactive. Taurodeoxycholate, at optimal concentration, produced a profound inhibition of oleate activation. Phospholipase D activity was detectable in all rat tissues investigated. The optimal incubation temperature for phospholipase D was 30 degrees C, with a break point at 16.1 degrees C in an Arrhenius plot.

The relationship between smoking and total immunoglobulin E levels

Abstract: Results of skin testing to common allergens, total serum IgE levels, and the responses to a respiratory questionnaire were obtained for 1768 individuals participating in a survey of a rural population. The geometric mean total IgE levels in a group of subjects without skin-test reactions and with no histories of asthma or hay fever was 14.8 U/ml for men and 11.9 U/ml for women. When individuals were classified according to skin reactivity and smoking history there was a significant difference in IgE levels among nonsmokers, exsmokers, and smokers, with smokers having the highest levels. The percentage of subjects with elevated total IgE levels was higher in smokers than in nonsmokers regardless of skin reactivity to common allergens. Among smokers there was no relationship between intensity and duration of smoking and IgE levels. Among exsmokers IgE levels tended to be lower in those who had stopped smoking earlier.

Dimension Theory for Ordered Sets

Abstract: In 1930, E. Szpilrajn proved that any order relation on a set X can be extended to a linear order on X. It also follows that any order relation is the intersection of its linear extensions. B. Dushnik and E.W. Miller later defined the dimension of an ordered set P = 〈X;≤〉 to be the minimum number of linear extensions whose intersection is the ordering ≤.

Confidants: Do They Make a Difference in Quality of Life?

Abstract: This article empirically explores the interrelations of three variables-sex, marital status, and the confidant relationship-and their joint effects on quality of life. It draws on a stratified rand...

The Cell Biology of Vitellogenic Follicles in Hyalophora and Rhodnius

Abstract: Insect oocytes assemble their protein yolk bodies by receptor-mediated endocytosis of specific extracellular proteins (Telfer, 1961; Anderson, 1964; Roth and Porter, 1964; other papers reviewed by Telfer, 1965; Engelmann, 1979; Hagedorn and Kunkel, 1979). The major constituent incorporated is the sex-limited hemolymph protein, vitellogenin, but smaller amounts of lipophorin and many other hemolymph proteins are also internalized (Telfer, 1960; Telfer et al., 1981a). In special cases, several apparent modifications of this general pattern have been described: In Drosophila melanogaster and related species a fraction of the total vitellogenin accumulated is apparently synthesized within the ovary (Bownes, 1980); in Hyalophora cecropia a secretory product of the follicle cells, now termed paravitellogenin, supplements the hemolymphderived proteins (Anderson and Telfer, 1969; Bast and Telfer, 1976; Rubenstein, 1979); the fine structure of Glossina austeni suggests that yolk in this species may be assembled primarily from follicle cell products (Huebner et al., 1975); and in some apterygotes fine structure implies that some yolk may be synthesized within the oocyte itself (Bilinski, 1977). While yolk formation in insects has thus evolved a certain amount of diversity, it is nevertheless clear that in most species vitellogenin synthesized by the fat body and transported through the hemolymph is the primary source of the protein that is amassed in the oocyte (reviewed by Engelmann, 1979; Hagedorn and Kunkel, 1979).

Diffraction of plane sh waves in a half‐space

Abstract: Scattering of antiplane shear waves (SH) in two dimensions by surface and near-surface defects in a homogeneous, isotropic elastic semi-infinite medium has been studied. Attention has been focused here in the range of medium to long wavelengths. A combined finite element and analytical technique has been used to study the problems of scattering by semi-circular and triangular canyons. The results for the former case are compared with the known exact solution and those for the latter case are compared with some available approximate solutions. Finally a problem of multiple scattering by a triangular canyon and a nearby circular tunnel is studied. Numerical results are presented showing the effects of multiple scattering and different angles of incidence. These results are of interest in earthquake engineering.

Parental Feeding of Nestling Yellow Warblers in Relation to Brood Size and Prey Availability

Abstract: The feeding by adult Yellow Warblers (Dendroica petechia) of nestlings in broods of 3, 4, or 5 young was studied during two breeding seasons on the forested dune ridge near Delta, Manitoba. Broods of 2-day-old young were selectively fed geometrid larvae by the adults, and broods of 8-day-old young were selectively fed chironomids and geo- metrid and other Lepidoptera larvae. The diet varied among broods of 3, 4, and 5 young at both ages, but this variation did not appear to affect the growth rates of the young. The total weight of items brought per half hour increased with brood size among broods of 2-day-old young. Broods of four 8-day-old young were fed the greatest amount of food. The diet of the nestlings is contrasted with the diet of adult Yellow Warblers observed in the same locality. Received 15 October 1980, accepted 19 October 1981.

Foraging-Flock Recruitment at a Black-Billed Gull Colony: Implications for the Information Center Hypothesis

Abstract: -The extent to which a flock leader advertises its departure from a colony and recruits flock mates is an important issue of the Information Center hypothesis. At a colony of Black-billed Gulls (Larus bulleri), I found that attractive calls were given by some leaders, that leaders called more often than followers, and that calling leaders recruited followers more often than silent leaders. Playback experiments demonstrated that these "contact" calls were attractive. The results indicate that some benefits, most likely related to group foraging, result from flock membership when the gulls are away from the colony. Benefits of group foraging away from the colony provide a more likely mechanism for explaining food-related selection pressures favoring a colonial foraging system than do the presumed benefits derived from the more complex, information-transfer mechanism envisaged by the Information Center hypothesis. Received 11 December 1980, accepted 1 July 1981. ACCORDING to the Information Center hypothesis described by Ward and Zahavi (1973), certain avian assemblages, such as communal roosts and breeding colonies, evolved primarily because they function as information centers where birds that have been unsuccessful in locating a good food patch can benefit by following other, more successful birds to the latters' food. The hypothesis is considered to apply mainly to birds that utilize food distributed in unpredictable but temporarily rich patches. Data consistent with the Information Center hypothesis have been obtained in studies of the Red-billed Dioch [Quelea] (Quelea quelea) (Ward 1965), the Great Blue Heron (Ardea herodias) (Krebs 1974, 1978), and the Bank Swallow (Riparia riparia) (Emlen and Demong 1975). The central concept of the Information Center hypothesis involves information transfer between or among birds at the roost or colony. Of particular relevance are signals whereby a potential leader might identify itself to followers. Although information transfer of the sort envisaged by the Information Center hypothesis could occur in the absence of specialized signals devoted to that function (Bertram 1978, Waltz in press), the extent to which a leader advertises its departure remains highly relevant to the hypothesis (Ward and Zahavi 1973). In this report, I examine some of the contexts and evolutionary implications of information transfer as it pertains to signals that could function as a means of flock recruitment at a colony and describe observations and experiments designed to assess the occurrence and probable function of these signals in Blackbilled Gulls (Larus bulleri). Black-billed Gulls nest in dense inland colonies in New Zealand (Stead 1932, Beer 1966, Evans 1970). They typically forage in flocks and utilize unpredictable but often temporarily rich food patches. Food items include fish, as well as worms and other small invertebrates that are exposed on open pasture land after rains or turned up on fields by farm implements (Dawson 1958, pers. obs.). SOME CONTEXTS FOR INFORMATION TRANSFER AT COLONIES Parasitic relationship.-A parasitic relationship would arise if followers that did not know where food was ("ignorant" birds) were able to victimize leaders that did know where food was ("knowledgeable" birds) by following them to their food patches, even though such information transfer were of no advantage to the leader (cf. Krebs 1978, Waltz in press). This situation could arise if a colony evolved and were maintained for reasons unrelated to information transfer, for example, if the colony provided protection against predators (Lack 1968). Possible costs to the leader might include those associated with leading potential competitors to the leader's food source. Even 24 The Auk 99: 24-30. January 1982 This content downloaded from 207.46.13.160 on Mon, 17 Oct 2016 05:19:47 UTC All use subject to http://about.jstor.org/terms January 1982] Flock Recruitment in Gulls 25 if such costs to the leaders were negligible, it is expected that knowledgeable leaders would not be selected to expend time and/or energy in advertising their departures. The occurrence of calls or other conspicuous recruitment displays by leaders would not be predicted in a parasitic system. Attempts by leaders to slink away quietly and inconspicuously would be more likely (Bertram 1978). Reciprocal altruism. -Information transfer could occur at a colony in a context of reciprocal altruism if a bird A leads another bird B to food on one trip, and bird B reciprocates and leads bird A to a food patch on some later trip (Krebs 1978). As pointed out by several investigators (Trivers 1971, Maynard Smith 1978, Davies and Krebs 1978, Vehrencamp 1979), however, systems based on reciprocal altruism are usually open to invasion by "cheaters." A cheater in the present situation can be defined as a bird that follows others to their food but does not lead others to any rich patches it might find itself. As in the parasitic situation, leaders in a system based on reciprocal altruism could face costs associated with leading competitors to the food supply and would not be predicted to expend time or energy in advertising their departures with calls or other recruitment displays. Cooperation between selfish leaders and followers.-A system in which knowledgeable leaders and ignorant followers all benefit is a third context in which information transfer at colonies could occur. This situation could arise whenever leaders would benefit directly from the company of flock members away from the colony site, for example, if flocking en route to the foraging grounds or while foraging were beneficial as an antipredator adaptation (Bertram 1978), or if group foraging were beneficial (Rand 1954, Fisher 1958). When these awayfrom-colony benefits of flocking occur, leaders and followers should all benefit by leaving in a flock. If leaving as a member of a flock is beneficial, leaders should be selected to recruit followers. This prediction is opposite to that derived from the previous two situations (parasitism and reciprocal altruism). TESTS OF PREDICTIONS The main predictions derived from the above theoretical considerations deal with the extent to which a potential flock leader should be selected to render itself conspicuous or inconspicuous to others when it leaves the colony on a foraging trip. Whenever a bird flies away from a colony, its actions necessarily provide information in the form of visual cues to any observers that might be watching. Vocalizations, in contrast, need not be given and, when present, can be taken as evidence for the emission of ritualized signals subject to positive selection pressures (Smith 1977) of the sort expected from a bird selected to make itself conspicuous, but not from one that is selected to be inconspicuous. Gulls, including the Black-billed Gull, are highly vocal, and preliminary observations indicated that loud calls are sometimes associated with foraging flocks. The occurrence of calls and their function when emitted were used to test the above predic-

Myth and the menopause

Abstract: This paper examines two competing descriptions of the menopausal experience, the one proffered by the medical profession and the other by the women's health movement. These different interpretations of the menopause are each treated as myths in the sense in which that term is used by Barthes. In his definition, myths are social products and the modern myth reflects the values of the bourgeoisie. Through an examination of these myths, the paper discusses the view of women, particularly ageing women, taken by the medical profession and by the feminist health movement.

The Control of Steroidogenesis by Human Fetal Adrenal Cells in Tissue Culture. IV.The Effects of Exposure to Placental Steroids

Abstract: The effect upon steroidogenesis of adding various steroids produced by the placenta was studied in short term cultures of human fetal adrenal cells. The addition of high concentrations (103 ng/ml) of estrone or estriol inhibited the production of cortisol, but only the former elicited a parallel increase in dehydroepiandrosterone (DHA) production. Estradiol was effective in inhibiting Δ4-3-ketosteroid production at concentrations of 10-100 ng/ml, levels which approach those found in the fetal circulation, while DHA production was increased at concentrations of 1 eg/ml. The addition of progesterone (4 eg/ml) to the medium caused increased production of cortisol and corticosterone, but had no effect on DHA production. Pregnenolone (4)eg/ml) increased the basal production of DHA and slightly impaired both basal and ACTH-stimulated aldosterone production, but had no effect on cortisol production. The data demonstrate that of the many fetal and placental factors which have been studied to date, only ACTH and e...

Immunoglobulin A deficiency: genetic studies.

Abstract: Immunoglobulin A (IgA) deficiency (less than 0.01 mg/ml) was demonstrated in 155 of 72,296 blood donors. Studies of families of 60 donors revealed IgA deficiency in other members of 12 families. No consistent pattern of inheritance of IgA deficiency was found. HLA typing of 62 unrelated IgA deficient blood donors showed a significant increase in the prevalence of HLA-B8 (p less than 0.005).

Evidence for the Involvement of Proton Motive Force in the Transport of Glucose by a Mutant of Streptococcus mutans Strain DR0001 Defective in Glucose-Phosphoenolpyruvate Phosphotransferase Activity

Abstract: Streptococcus mutans DR0001 and a glucose-phosphotransferase (PTS)-defective mutant, DR0001/6, were grown anaerobically in a chemostat with a glucose limitation at dilution rates (D) of 0.04 to 0.6 h−1 (mean generation time, 17 to 1.2 h). The mutant possessed only 15% of glucose-PTS activity of the wild type and gave cell yields (19%) less than those of the wild type. Glucose-PTS activity in strains DR0001 was maximum at D = 0.1 h−1 and was adequate to account for transport in the chemostat at all dilution rates except D = 0.6 h−1, at which it was 80% of the actual glucose uptake activity. The mutant DR0001/6, on the other hand, possessed only sufficient glucose-PTS activity to sustain growth at below D = 0.1 h−1, indicating the presence of an alternate transport activity. This was confirmed in glycolytic rate experiments with washed cells, which demonstrated that the mutant showed rates 11- to 27-fold higher than that accountable via glucose-PTS activity alone. The wild-type organism contained both a high (Ks, 6.7 to 8.0 μM)- and a low (Ks, 57 to 125 μM)-affinity transport system, whereas the glucose-PTS-defective mutant contained only the low-affinity system (Ks, 62 to 133 μM). The glucose-PTS was shown to be the high-affinity system. Glucose uptake by the mutant was unaffected by 8 mM sodium arsenate, 10 mM azide, and 10 mM dinitrophenol but was completely inhibited by 0.05 mM sodium iodoacetate. Glycolysis in the organism was almost completely inhibited by 0.25 mM N′,N′ -dicyclohexylcarbodiimide (DCCD), indicating the involvement of an ATPase in glucose uptake. The ionophores carbonylcyanide-m-chlorophenylhydrazone and tetrachlorosali-cylanilide were inhibitory at concentrations of 10 μM, suggesting that a proton gradient was important in the transport process. Higher levels of DCCD and the ionophores were required to inhibit the wild-type organism to the same degree. A mechanism is proposed for the alternative transport system whereby proton motive force is created by the extrusion of protons by the DCCD-sensitive ATPase and glucose is transported down a proton gradient in a symport with protons.

Dynamics of Seabird Multispecies Feeding Flocks: Age-Related Feeding Behaviour

Abstract: Multispecies feeding flocks of seabirds were studied in Barkley Sound, British Columbia. The flocks occurred during the post-breeding dispersal of migrant adult and juvenile seabirds. A consideration of comparative foraging success indicated that juvenile seabirds were less skilled at locating and capturing prey. Juveniles did not initiate flocks, were less adept at finding food, and had lower feeding success rates. The juveniles appeared to compensate for these inadequacies by using a different foraging strategy than adults. They increased the amount of time spent feeding and appeared to be more attracted to the presence of other feeding birds. Juveniles were less able to recognize good potential feeding areas and accessible food items. Juveniles had a greater tendency to loaf on the centrally located terrestrial loafing sites, thus increasing their chances of sighting feeding flocks. Our results demonstrated how improved post-fledging survival was achieved for juvenile seabirds feeding in the flocks. Our findings support the interpretations put forth by others to explain delayed maturity, reduced clutches in younger birds and prolonged parental care, all characteristic of seabirds.

Intracellular localization of prolactin receptor and prolactin in the rat ovary by immunocytochemistry.

Abstract: The localization of the PRL receptor as well as of PRL has been studied by immunoperoxidase techniques in the ovaries of cycling, pregnant, and lactating rats. Specific antisera to the receptor and to the hormone were used. By light microscopy, immunostaining for the PRL receptor coincided with that for the hormone. Staining was found intracellularly in most components of the ovary, except the theca, and was most striking in the luteal cells. Both PRL and its receptor were concentrated heavily in the ovum. Beginning 24–36 h postpartum, there was a change in the pattern of luteal cell staining, with a shift in the intensity of staining products to the periphery of the luteal cell, giving a ring appearance to these cells. The results suggest roles for PRL in ovarian function involving both maintenance of the corpus luteum and maturation of the ovum. This study also demonstrates the intracellular localization of a polypeptide hormone in association with its specific receptor.