PubMed Health⌕ Search

Biomedical subjects

M Bernier

Publications and source records attributed to M Bernier.

113 records · Page 7Linked to original sources
PubMedDate not supplied

Manipulation of myocardial alpha-tocopherol levels fails to affect reperfusion arrhythmias or functional recovery following ischemic challenge in the rat heart.

Antioxidants that act as free radical scavengers have the potential to inhibit lipid peroxidation. It has previously been proposed that a relationship exists between free radicals, lipid peroxidation and reperfusion-induced arrhythmias. We have therefore examined the ability of the lipid-soluble antioxidant, alpha-tocopherol, to decrease the incidence of reperfusion-induced arrhythmias. We have shown that the myocardial alpha-tocopherol content can be significantly increased from its control value of 65.3 +/- 5.6 nmoles/g wet wt of heart to 115.0 +/- 15.6 nmoles/g wet wt of heart (p less than 0.01) by chronic intraperitoneal pretreatment and that it can be decreased, to 21.1 +/- 3.7 nmoles/g wet wt of heart (p less than 0.01), by chronic dietary manipulation. Rat hearts isolated from either of these groups, or from placebo-treated control animals, were subjected to 5 or 10 min coronary artery occlusion and were subsequently reperfused; there were no significant differences between the incidence and duration of VF and VT or the incidence and number of VPBs in these three groups. The effect of alpha-tocopherol manipulation on metabolic and functional recovery of working hearts subjected to 20 min global ischemia was subsequently examined and no significant changes were observed. Cardiac output recovered to 82 +/- 4, 81 +/- 6 and 76 +/- 5% of its preischemic value in the control, enriched and depleted groups, respectively. In conclusion, myocardial alpha-tocopherol content appears to bear no relation to the severity of reperfusion-induced arrhythmias or to the resistance of the heart to ischemic injury.

Adenosine Triphosphate↗
PubMedDate not supplied

Steroidogenesis of cultured purified pig Leydig cells: secretion and effects of estrogens.

Using a primary culture of purified immature pig Leydig cells we have demonstrated: (1) that during the first 3 days of culture there is a 'spontaneous' maturation of the steroidogenic response to hCG, as expressed by a 50-fold increase of the steroidogenic capacity, an increased secretion of both dehydroepiandrosterone sulfate (DHAS) and testosterone (T), a shift of the DHAS/T ratio (5 on day 0 vs. 0.5 on day 3) without significant changes in the number of hCG-binding sites; (2) that purified cells, on day 3 following hCG stimulation, secrete large amounts of T and small amounts of E2 (T/E2 congruent to 150) and detectable amounts of estrone, while crude pig interstitial cells under the same conditions secrete less T but 40-50 times more estrogens (T/estrogens congruent to 1.5); (3) that the steroidogenic responsiveness of purified Leydig cells is not impaired by E2 treatment, in spite of the fact that Leydig cells contain specific estradiol receptors (approximately 10000 sites/cell). These data suggest that in this model the main source of testicular estrogens are not Leydig cell but some other testicular cell types, and that the lack of effect of estrogens on pig Leydig cell steroidogenesis is not due to absence of estrogen receptors.

Androgens↗
PubMedDate not supplied

[Street children and AIDS in Haiti].

This study is a qualitative inquiry KAP about sexuality, and adoption and preservation of safe sexual behaviors, among the children of the street in Port-au-Prince, Haiti. Three groups of participating children of the street were observed in Port-au-Prince for three months, during June through August 1991. The information was collected with the use of pre-tested charts for each theme chosen. Then, individual interviews were conducted with leaders identified among the educators and children of the street. One of the main goals of Aids educational programs of street children should be to make them believe in the existence of the disease, and the real risk it poses for death. The strategies that we will use to convince them should deal with the different social, psychological, economical, and environmental factors that characterized the children as follows: 1) their adherence to a peer group and the relationship of power between the older and younger children; 2) the fundamental importance of money in their life, and that all relationships that they have are based on the capacity of people to give them something, such as money; 3) the role of their social appearance and their need to behave like other children for even one day; 4) their low self-esteem; 5) their feeling of powerlessness and resignation related to their living conditions; 6) the influence of the street culture; and 7) their understanding of sexuality as an immediate pleasure.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Specific inhibition of insulin receptor dephosphorylation by a synthetic dodecapeptide containing sulfotyrosyl residues as phosphotyrosyl mimetic.

We have synthesized a tris-sulfotyrosyl dodecapeptide (3S-peptide-I) that corresponds to the major autophosphorylation domain within the insulin receptor beta-subunit and showed that it potently inhibited insulin receptor dephosphorylation by protein tyrosine phosphatases (PTPases) in vitro. 3S-peptide-I also inhibited tyrosine dephosphorylation of a synthetic peptide by the recombinant PTPase PTP-1B, indicating that 3S-peptide-I interacts directly with PTPase, causing its inactivation. The peptide had no effect on the activity of serine/threonine phosphatases, PP-1 and PP-2A, or alkaline phosphatase. Furthermore, we found that the introduction of a N-stearyl derivative of 3S-peptide-I in CHO/HIRc cells caused a significant increase in insulin-stimulated phosphorylation of the insulin receptor. In contrast, ligand-stimulated phosphorylation of epidermal growth factor (EGF) receptor in CHO cells overexpressing EGF receptors was not affected by the presence of N-stearyl-3S-peptide-I. These data suggest that by inhibiting dephosphorylation of the insulin receptor in intact cells, 3S-peptide-I may specifically enhance insulin signalling.

Amino Acid Sequence↗