Biomedical subjects

J Beaulieu

Publications and source records attributed to J Beaulieu.

18 recordsLinked to original sources

PubMed2003

Cross-species amplification of mitochondrial DNA sequence-tagged-site markers in conifers: the nature of polymorphism and variation within and among species in Picea.

Primers previously developed to amplify specific non-coding regions of the mitochondrial genome in Angiosperms, and new primers for additional non-coding mtDNA regions, were tested for their ability to direct DNA amplification in 12 conifer taxa and to detect sequence-tagged-site (STS) polymorphisms within and among eight species in Picea. Out of 12 primer pairs, nine were successful at amplifying mtDNA in most of the taxa surveyed. In conifers, indels and substitutions were observed for several loci, allowing them to distinguish between families, genera and, in some cases, between species within genera. In Picea, interspecific polymorphism was detected for four loci, while intraspecific variation was observed for three of the mtDNA regions studied. One of these (SSU rRNA V1 region) exhibited indel polymorphisms, and the two others ( nad1 intron b/c and nad5 intron1) revealed restriction differences after digestion with Sau3AI (PCR-RFLP). A fourth locus, the nad4L- orf25 intergenic region, showed a multibanding pattern for most of the spruce species, suggesting a possible gene duplication. Maternal inheritance, expected for mtDNA in conifers, was observed for all polymorphic markers except the intergenic region nad4L- orf25. Pooling of the variation observed with the remaining three markers resulted in two to six different mtDNA haplotypes within the different species of Picea. Evidence for intra-genomic recombination was observed in at least two taxa. Thus, these mitotypes are likely to be more informative than single-locus haplotypes. They should be particularly useful for the study of biogeography and the dynamics of hybrid zones.

Base Sequence↗

PubMed2003

Somatic stability of microsatellite loci in Eastern white pine, Pinus strobus L.

Variation at nuclear- and chloroplast-encoded microsatellite loci was studied among and within clonally propagated individuals of Eastern white pine. Total DNA was extracted and assayed from gamete-bearing tissue (megagametophytes) located on six different branch positions on each of 12 individual genets. No within-individual variation was observed among 12 loci studied. Estimates of numbers of mitotic cell divisions required to produce the tissue used as the source of genomic DNA were obtained by combining tree growth and anatomical data. This allowed for the calculation of upper bound estimates of numbers of mutations per locus per somatic cell division. The estimated somatic mutation rate was found to be substantially lower than those published for genomic microsatellite mutation rates in other plant species.

Genetic Variation↗

PubMed2001

Contrasting evolutionary forces driving population structure at expressed sequence tag polymorphisms, allozymes and quantitative traits in white spruce.

Patterns of variation in quantitative characters and genetic markers were compared among six regional populations of white spruce [Picea glauca (Moench) Voss]. Although some phenotypic characters were correlated with latitude (r = 0.791), longitude (r = -0.796) and precipitation during the growing season (r = 0.789), variability at genetic markers was not correlated with geographical or bioclimatic variables, and followed neutral expectations. Estimates of genetic diversity and population differentiation for 14 allozymes (translated regions of coding genes) were essentially indistinguishable from those observed for 11 expressed sequence tag polymorphisms (ESTPs) from untranslated regions of coding genes. Variation among populations for quantitative traits such as eighth year height (Q(ST) = 0.082), thirteenth year height (Q(ST) = 0.069), total wood density (Q(ST) = 0.102) and date of budset (Q(ST) = 0.246), was greater than for allozymes (G(ST) = 0.014) and ESTPs (G(ST) = 0.019). These trends suggest a strong adaptive response in quantitative traits, contrasting to allozymes and ESTPs where no selective response could be detected and where populations appeared to be essentially in a migration-drift equilibrium.

DNA, Plant↗

PubMed2001

[Mobilizing community around the lack of preventive measures against crime among 10- and 11-year-old children].

Originality and relevance are not the only factors in the success of innovative programs. Community consensus, expertise and credibility of staff, and evaluative approaches are important as well. Virgule ("Comma"), a program aimed at helping 10- and 11-year-olds who are first offenders, has these characteristics. The temporary hitch in the youth's life is viewed not as a definitive failure but as an opportunity for change. This is Virgule's philosophy: "Changing a period into a comma means changing a difficulty into a reason for progress."

Adolescent↗

PubMed2000

[Time management: realities for parents living with children with motor deficiencies].

A quantitative study involving 244 families from three health and social service regions of Quebec was undertaken to explore how families function. Fourteen families agreed to participate in the qualitative part of this study. Twenty-eight parents participated through an in-depth interview. During the interviews, the impact of the presence of a child with a motor disability on the parents' use of time was discussed. An analysis of the themes and categories highlighted the different aspects of the impact of a handicapped child on the parents' use of time in relation to the four spheres of life. In fact, the parents that were interviewed indicated that the presence of their child greatly influenced the time they had available for their personal, conjugal and family life as well as for doing any paid work. In general, mothers devoted more time than fathers to the care of the child. This situation has a direct impact on the way the mothers manage their time. Based on an analysis of the respondents' comments, the author recommends to offer support to the parents in order to assist them with time management.

Activities of Daily Living↗

PubMed1999

Susceptibility to FAS-induced apoptosis in human nontumoral enterocytes: role of costimulatory factors.

FAS-FAS ligand interaction has been implicated in increased enterocyte apoptosis seen in immune-mediated bowel injury. However, scant information exists on the role of FAS in physiological enterocyte turnover. In the present study, the regulation of enterocyte FAS and FAS ligand expression by cytokines and its functional role in human intestinal epithelial cell apoptosis and proliferation were analyzed with two different models: a nontransformed human intestinal epithelial cell line (HIEC) and normal colonic explant cultures. HIEC constitutively expressed FAS, as analyzed by flow cytometry. However, stimulation with agonistic anti-FAS antibody (1-500 ng/ml) did not induce HIEC apoptosis. In contrast, in the presence of tumor necrosis factor alpha (TNFalpha) and/or interferon gamma (IFNgamma), HIEC became highly susceptible to FAS-induced apoptosis. The sensitizing effect to FAS-induced apoptosis was mediated via TNFalpha- and IFNgamma-induced upregulation of FAS expression (maximally 348%). Receptor studies showed that the effect of TNFalpha on FAS was mediated via the p55 TNF receptor. In colonic organ cultures, IFNgamma and TNFalpha also enhanced colonocyte FAS expression, resulting in a markedly increased apoptotic response to stimulation of this receptor, as shown by in situ terminal deosyuridine triphosphate nick-end staining. Neither FAS ligand expression nor its induction by cytokines was observed in HIEC or colonic explants. Proliferation studies showed that FAS is not implicated in regulating HIEC growth. These findings suggest that, despite the fact that normal human enterocytes express FAS, costimulatory factors, such as TNFalpha or IFNgamma, abundantly secreted under inflammatory conditions, are necessary to sensitize intestinal epithelial cells to FAS-induced apoptosis by upregulating this receptor.

Antigens, CD↗

PubMed1998

CRFergic innervation of the paraventricular nucleus of the rat hypothalamus: a tract-tracing study.

It has been reported that corticotropin-releasing factor (CRF) may regulate its own biosynthesis in the paraventricular nucleus of the hypothalamus (PVH). Whether this CRF autoregulation is mediated by local circuitry or from extra-PVH CRF neuronal fibers terminating on CRF perikarya within the PVH is unknown. In the present study, we sought to determine the origin(s) of this CRF innervation using retrograde transport of wheat germ-conjugated-gold particles (WGA-apoHRP-Au) combined with immunohistochemistry for CRF. The rats also received colchicine (100 microg, icv) 5-7 days after tracer injection and were perfused 24 h later. Results of retrograde labeling with pressure injections of WGA-apoHRP-Au centered to PVH and subsequent immunohistochemical staining for CRF demonstrated numerous retrogradely labeled CRF neurons in the perifornical hypothalamic nucleus (PeF), the dorsolateral hypothalamic area (DA) (medial and lateral portions) and the dorsomedial nucleus of the hypothalamus (DMH). Smaller groups of CRF-ir neurons that were retrogradely labeled were found in the bed nuclei of the stria terminalis (BnST), the Barrington's nucleus (Bar) and the dorsal raphé (DR). These CRFergic pathways to the PVH may represent an anatomical substrate underlying the function of the stress-integrative PVH neurons in the autonomic, behavioral and neuroendocrine regulation during the stress response, including CRF autoregulation.

Animals↗

PubMed1996

Expression and turnover of an interstitial matrix component of the pericryptal sheath in neonatal mice.

The aim of the present study was to determine the expression and turnover of antigen 1/130, a component of the interstitial matrix associated with collagen fibrils in the pericryptal sheath, in neonatal mice (CD1). Anti-laminin was used as a control. Starting on day 9 after birth, monoclonal antibody 1/130 (Mab-1/130) or anti-laminin were either fed orogastrically or injected intraperitoneally twice daily for 3 days. Bound immunoglobulins were disclosed by indirect immunofluorescence at days 12, 16, 23, 30 and 40. Sections from duodenum, ileum and colon were incubated together on the same glass slide. At day 12, the levels of labelling in orogastrically fed animals with Mab-1/130 exhibited a proximo-distal gradient (duodenum>ileum>colon); labelling with anti-laminin was found in the duodenum only. In injected animals, the levels of labelling with both antibodies showed the same gradient (duodenum>ileum>colon). At day 23, Mab-1/130 was still detected in both groups in the duodenum and ileum, whereas anti-laminin was barely detectable and only in the duodenum. At day 30, in animals fed as above or injected intraperitoneally, Mab-1/130 was present in the duodenum at the bottom of the crypts; anti-laminin was completely absent. During the postnatal period, the turnover of antigen-1/130 appeared to be slow and, as the crypts elongated, the mesenchymal pericryptal sheath did not co-migrate with the epithelial cells.

Animals↗

PubMed1996

Enkephalin innervation of the paraventricular nucleus of the hypothalamus: distribution of fibers and origins of input.

The opioid peptide enkephalin emerges as a major neuromodulator in the regulation and integration of the physiologic response in stressful conditions. The paraventricular nucleus of the hypothalamus is a coordinating center of neuroendocrine and autonomic functions. However, the detailed distribution of the enkephalin fibers and terminals in the paraventricular nucleus and the sources of enkephalinergic innervation are not well defined. In the present study, we used immunocytochemistry for the proenkephalin-derived octapeptide met-arg6-gly7-leu8 enkephalin to determine the distribution of enkephalin-immunoreactive fibers and somata within paraventricular nucleus. Without colchicine pretreatment, enkephalinergic fibers were prominent mainly in the ventromedial part of the parvicellular subdivision of the paraventricular nucleus, appearing in coronal sections as a dense collection of short segments of enkephalin-immunoreactive fibers. In the periventricular portion of the paraventricular nucleus, enkephalin-immunoreactive fibers produced a moderate plexus of short enkephalin-immunoreactive fibers dorsoventrally oriented. With colchicine treatment, a dense cluster of enkephalin-immunoreactive cell bodies was located in the dorsomedial and the dorsal parts of the parvicellular subdivisions. These enkephalin-immunoreactive neurons were small (< 10 microns) to medium sized (10-15 microns), with round and elongated shapes. Retrograde transport of wheat germ-conjugated gold particles, WGA-apoHRP-Au, from the paraventricular nucleus, combined with immunocytochemistry for enkephalin revealed that the major sources of extrahypothalamic enkephalin afferents to the paraventricular nucleus are provided by enkephalin neurons in the lateral reticular nucleus and the paragigantocellularis reticular nucleus of the medulla (approximately 20% of retrogradely labeled neurons within this nucleus were double labeled) and in the nucleus solitary tract (approximately 10% of retrogradely labeled neurons within this nucleus were double labeled). Retrogradely labeled enkephalin neurons were also observed in the medial preoptic area, median preoptic nucleus, dorsomedial hypothalamic nucleus, lateral septum and hypothalamic arcuate nucleus. These enkephalinergic pathways from the medulla and the forebrain could represent an anatomical substrate underlying the opioid effects on paraventricular neurons during physiological processes, such as cardiovascular regulation, feeding or stress responses.

Afferent Pathways↗

PubMed1996

Quantification of circulating 1,25-dihydroxyvitamin D by radioimmunoassay with 125I-labeled tracer.

We report here the first RIA for 1,25-dihydroxyvitamin D utilizing a radioiodinated (125I) tracer. This is also the first validated RIA for 1,25-dihydroxyvitamin D [1,25(OH)2D] that does not require sample prepurification by HPLC before the binding assay. The assay involves acetonitrile extraction, treatment of the crude extract supernate with sodium periodate, extraction and purification of endogenous 1,25(OH)2D by solid-phase chromatography, and finally, quantification by RIA. Calibrators were prepared in stripped human serum and processed exactly the same as samples, eliminating the need for internal control for procedural losses of endogenous 1,25(OH)2D. The assay consists of a 2-h room temperature incubation with the primary antibody, a 20-min incubation with a second antibody, and separation of bound from free by centrifugation. Assay results can be in hand with 5 h. The detection limit of the assay is 2.4 ng/L 1,25-dihydroxyvitamin D3. Results compare well with those from an accepted radioreceptor assay. Sample pretreatment with sodium periodate is absolutely essential before quantification by RIA; otherwise, concentrations of endogenous 1,25(OH)2D may be greatly overestimated.

Acetonitriles↗

PubMed1995

Complete congruence between gene diversity estimates derived from genotypic data at enzyme and random amplified polymorphic DNA loci in black spruce.

Controversy still exists over the adaptive nature of variation of enzyme loci. In conifers, random amplified polymorphic DNAs (RAPDs) represent a class of marker loci that is unlikely to fall within or be strongly linked to coding DNA. We have compared the genetic diversity in natural populations of black spruce [Picea mariana (Mill.) B.S.P.] using genotypic data at allozyme loci and RAPD loci as well as phenotypic data from inferred RAPD fingerprints. The genotypic data for both allozymes and RAPDs were obtained from at least six haploid megagametophytes for each of 75 sexually mature individuals distributed in five populations. Heterozygosities and population fixation indices were in complete agreement between allozyme loci and RAPD loci. In black spruce, it is more likely that the similar levels of variation detected at both enzyme and RAPD loci are due to such evolutionary forces as migration and the mating system, rather than to balancing selection and overdominance. Furthermore, we show that biased estimates of expected heterozygosity and among-population differentiation are obtained when using allele frequencies derived from dominant RAPD phenotypes.

Alleles↗

PubMed1995

[Relationship between exposure to stress and development of hypertension].

The relationship between stress and hypertension has long been a topic of debate. Until recently, no animal (nor physical) model existed which incorporated these two parameters together, hence accurate assessments of their interactions were postulations, at best. The borderline hypertensive rat (BHR) is an animal model in which arterial hypertension will ensue only when the rat is subjected to a chronic stressor. Therefore, this animal model offers an opportunity to study the physiological consequences of a given stressor on the entire organism during the course of the development of hypertension. The cardiovascular and humoral effects of chronic exposure to a physiological stressor on the BHR, at rest and during exposure to an acute and novel stress, have been examined and are presented in this paper. The involvement of the central nervous system in the regulation of this stress induced hypertensive state has been hypothesized to play a major role in the regulation of the stress and hypertensive relationship. Of particular importance are the endogenous opioids and their influence on the maintenance of homeostasis during periods of physiological stress. The localization of the endogenous opioid enkephalin in the paraventricular nucleus of the hypothalamus (PVN), an important brain region in the regulation of the stress response further substantiates the involvement of the opioid system during stress induced hypertension. Immunohistochemical data on the localization of ENKergic fibers in the PVN and other brain regions are similarly discussed in this paper.

Animals↗

PubMed1988