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Results for “differential selection”

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PubMed2004

Early childcare and physical aggression: differentiating social selection and social causation.

BACKGROUND: Some research findings have suggested that group day-care may be associated with an increased risk for physical aggression. METHODS: Cross-sectional maternal questionnaire data from a representative sample of 3431 Canadian 2- to 3-year-olds were used to compare rates of physical aggression shown by children looked after by their own mothers and those attending group day-care. A family risk index (using occupational level, maternal education, size of sibship, and family functioning) was created to test whether any difference in physical aggression might reflect social selection rather than social causation. RESULTS: Aggression was significantly more common in children looked after by their own mothers than in those attending group day-care. Strong social selection associated with family risk was found, not only in the sample as a whole, but even within the high-risk subsample. However, after taking social selection into account, physical aggression was significantly more common in children from high-risk families looked after by their own parents. No such difference was evident in the majority (84%) of children from low-risk families. CONCLUSION: Insofar as there are any risks for physical aggression associated with homecare they apply only to high-risk families.

Age Factors↗
PubMed1999

Differential and selective inhibition of protein kinase A and protein kinase C in intact cells by balanol congeners.

The fungal metabolite balanol is a potent inhibitor of protein kinase A (PKA) and protein kinase C (PKC) in vitro that acts by competing with ATP for binding (K(i) approximately 4 nM); congeners of balanol show specificity for PKA over PKC. We have characterized the effects of balanol and 10"-deoxybalanol in intact cells to determine whether these compounds cross the cell membrane and whether the potency and specificity noted in vitro are preserved in vivo. In neonatal rat myocytes and cultured A431 cells transiently transfected with a cyclic AMP response element-luciferase reporter construct, balanol inhibits the induction of luciferase activity by isoproterenol, indicating inhibition of PKA. Western analysis shows that both balanol and 10"-deoxybalanol reduce phosphorylation of cAMP response element-binding protein in isoproterenol-stimulated A431 cells; inhibition is concentration dependent with an IC(50) value of approximately 3 microM. Balanol, but not 10"-deoxybalanol, inhibits phosphorylation of the myristoylated alanine-rich C kinase substrate protein, a PKC substrate, in phorbol ester-stimulated A431 cells (IC(50) approximately 7 microM). Our data demonstrate that balanol is a potent inhibitor of PKA and PKC in several whole-cell systems and causes no obvious toxicity. In addition, balanol congeners inhibit PKA and PKC with the specificity and potency predicted by in vitro experiments.

Animals↗
PubMed1996

A selective and differential medium for Vibrio harveyi.

A new medium, termed Vibrio harveyi agar, has been developed for the isolation and enumeration of V. harveyi. It is possible to differentiate V. harveyi colonies from the colonies of strains representing 15 other Vibrio species with this medium. This medium has been shown to inhibit the growth of two strains of marine Pseudomonas spp. and two strains of marine Flavobacterium spp. but to allow the growth of Photobacterium strains. Colonies displaying typical V. harveyi morphology were isolated from the larval rearing water of a commercial prawn hatchery with V. harveyi agar as a primary isolation medium and were positively identified, by conventional tests, as V. harveyi. This agar displays great potential as a primary isolation medium and offers significant advantages over thiosulfate-citrate-bile salts-sucrose agar as a medium for differentiating V. harveyi from other marine and estuarine Vibrio species.

Culture Media↗
PubMed1983

Evaluation of differential and selective media for isolation of Aeromonas and Plesiomonas spp. from human feces.

We studied nine solid and two liquid media for their suitability to select Aeromonas and Plesiomonas spp. from human stools, using artificially contaminated samples as well as 254 samples from outpatients with and without diarrhea. Media with optimal sensitivity and specificity for Aeromonas spp. were alkaline peptone-water, Trypticase soy broth with ampicillin, inositol-brilliant green-bile salts agar, dextrin-fuchsin-sulfite agar, xylose-sodium desoxycholate-citrate agar, and Pril-xylose-ampicillin agar. For Plesiomonas sp., alkaline peptone-water and inositol-brilliant green-bile salts agar were optimal. Four strains of Aeromonas spp. were detected in patient samples with these media.

Aeromonas↗
PubMed1997

Mitogen-activated and cyclin-dependent protein kinases selectively and differentially modulate transcriptional enhancement by the glucocorticoid receptor.

Cyclin-dependent kinase (CDK) and mitogen-activated protein kinase (MAPK) phosphorylate the rat glucocorticoid receptor in vitro at distinct sites that together correspond to the major phosphorylated receptor residues observed in vivo; MAPK phosphorylates receptor residues threonine 171 and serine 246, whereas multiple CDK complexes modify serines 224 and 232. Mutations in these kinases have opposite effects on receptor transcriptional activity in vivo. Receptor-dependent transcriptional enhancement is reduced in yeast strains deficient in the catalytic (p34CDC28) or certain regulatory (cyclin) subunits of CDK complexes and is increased in a strain devoid of the mammalian MAPK homologs FUS3 and KSS1. These findings indicate that the glucocorticoid receptor is a target for multiple kinases in vivo, which either positively or negatively regulate receptor transcriptional enhancement. The control of receptor transcriptional activity via phosphorylation provides an increased array of regulatory inputs that, in addition to steroid hormones, can influence receptor function.

Animals↗
PubMed1991

Optimal growth temperature for the isolation of Plesiomonas shigelloides, using various selective and differential agars.

The growth characteristics of known strains of Plesiomonas shigelloides were compared with those of Aeromonas species (the major competing species in environmental waters) on plesiomonas differential agar, inositol brilliant green bile salt, and modified salmonella-shigella agar at incubation temperatures of 37, 42, and 44 degrees C. Using local isolates from clinical and environmental sources, optimal growth conditions, as determined by colony counts and the colony characteristics, plesiomonas differential agar proved to be ideal when incubated at 44 degrees C. Contrary to earlier recommendations for 48 h incubation, the colonies could be recognized readily after an incubation of 24 h.

Agar↗
PubMed2003

Experimental analysis of students' course selection.

BACKGROUND: Prior to every term, students must select courses (i.e., academic units of instruction within a degree programme) to determine their study programme. Course selection (CS) is a sequential decision-making (DM) process--students weigh various types of information available about each course. Every decision influences the weighting of considerations for the next. This study is focused on three central dimensions of CS: Learning Value (low or high in being intellectually challenging, interesting and thought-provoking), Lecturer's Style (low or high--exciting, charismatic and humorous versus dry, inflexible, unclear, etc.), and Course Difficulty (easy, moderate or hard). AIMS: (1) To examine students' preferences for each dimension in five choices and in their sequential location (1st to 5th). (2) To trace compromises in dilemma situations after the desirable combinations had already been selected. (3) To investigate differential selection as a function of students' age, gender, and academic standing (average grades). SAMPLE: Advanced undergraduates in various departments in an Israeli university (N = 1,007). METHOD: In an experimental design, respondents were presented with 12 course descriptions representing 2x2x3 combinations, and asked to select five courses in a sequential order. RESULTS: The 12 courses were found to be empirically divided into: ideal courses (2), first-degree (4) and second-degree (4) compromises, and rejected courses (2). Students avoided selecting hard courses unless they had no choice. Learning Value was the most preferred dimension, followed closely by Lecturer Style. Correlations showed that older and higher achieving students chose more difficult and high Learning Value courses. COMMENTS: The discussion centred on the methodological issue of the effectiveness of an experimental design for the investigation of CS, conceptual issues concerning Course Difficulty in students' selection and evaluation, and applied issues concerning the availability of information about the three investigated dimensions to students in real-life CS.

Choice Behavior↗
PubMed2000

Use of evoked potentials to objectively differentiate between selective vulnerability of cochlear and vestibular end organ function.

Auditory nerve brainstem evoked responses (ABR) have been used for several decades to investigate cochlear function. Recently techniques have been developed to elicit similar recordings from the vestibular end organs - short latency vestibular evoked potentials (VsEPs). Both ABR and VsEP reflect appropriate end organ function and may therefore be used to investigate the vulnerability of these end organs to various experimental insults, such as noise exposure and ototoxic drugs.

Animals↗
PubMed2000

IL-15 and IL-15 receptor selectively regulate differentiation of common mucosal immune system-independent B-1 cells for IgA responses.

We show in this report a new regulatory role for IL-15 and IL-15R in the development of B-1 cells and their differentiation into IgA-producing cells. Mucosal IgA levels were found to be inhibited by anti-IL-15 mAb treatment in vivo, but enhanced by administration of rIL-15, while serum IgA levels remained unaffected. Mucosal B-1 cells preferentially proliferated in response to IL-15 in vitro. When mucosal B-1 and B-2 cells were separated into surface (s)IgM(+)sIgA(-) and sIgM(-)sIgA(+) fractions, IL-15R-specific mRNA was found to be predominant in both sIgM(+)sIgA(-) and sIgM(-)sIgA(+) B-1 cells at a much higher level than B-2 cells. Further, incubation of these different subsets of B-1 and B-2 cells with IL-15 resulted in greater enhancement of the corresponding receptor expression by B-1 subset when compared with B-2 fraction. Interestingly, de novo isolated sIgM(+)sIgA(-) B-1, but not sIgM(+)sIgA(-) B-2, cells were already class-switched cells because the germline Calpha transcript was detected and was then further enhanced by IL-15. IL-15 also supported differentiation of both sIgM(+)sIgA(-) and sIgM(-)sIgA(+) B-1 cells into IgA-producing cells. Taken together, these findings suggest that IL-15 is a critically important cytokine for the differentiation of both sIgM(+),IgA(-) and sIgM(-)sIgA(+) B-1 cells expressing IL-15R into IgA-producing cells in mucosal tissues.

Animals↗
PubMed1989

Fenfluramine selectively and differentially decreases the density of serotonergic nerve terminals in rat brain: evidence from immunocytochemical studies.

Fenfluramine is an amphetamine derivative which is used primarily as an anorectic agent in the treatment of obesity. High doses of fenfluramine have been reported to cause long-term decreases in brain serotonin (5-HT) levels and density of high-affinity 5-HT uptake sites, actions characteristic of a "neurotoxic" effect of the drug. In view of these neurochemical changes, we used immunocytochemistry to assess, in detail, the effects of fenfluramine treatment on the morphology and density of 5-HT-like immunoreactive neurons in rat brain. Twelve to 18 hr after high dose dl-fenfluramine HCl treatment (24 mg/kg s.c., twice daily for 4 days), there was a profound regional decrease in density of fine-caliber 5-HT-like immunoreactive fibers and terminals in brain. This effect was especially apparent in cerebral cortex, hippocampus, cerebellum and striatum and less striking decreases were noted in septum, locus ceruleus and hypothalamus. On the other hand, 5-HT-like immunoreactive somata in midbrain nuclei and fibers and terminals in spinal cord appeared unaffected after fenfluramine treatment. Remaining 5-HT-like immunoreactive fibers and terminals displayed morphology characteristic of degenerating axons (thickening, swollen varicosities and fragmentation). Two weeks after the 4-day treatment regimen, patterns of 5-HT-like immunostaining appeared similar to those noted immediately (i.e., 18 hr) after drug treatment; however, the presence of grossly deformed fibers and terminals seen shortly after drug treatment was lacking. Tyrosine hydroxylase-like immunoreactivity, used to assess changes in catecholamine-containing neurons, appeared unaffected by drug treatment. These data suggest that, in rats, high s.c. doses of fenfluramine may be neurotoxic to some 5-HT-like immunoreactive axons and terminals. The relevance of these observations to the continued therapeutic use in humans of smaller p.o. doses of fenfluramine remains to be determined.

Animals↗