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M Lafrance

Publications and source records attributed to M Lafrance.

17 recordsLinked to original sources
PubMed2002

[Prior use of a telephone-nursing triage service by patients of emergency services].

OBJECTIVES: A province-wide telephone-nursing triage service was implemented in Quebec, Canada, in order, among other objectives, to decrease overcrowding in hospital emergency rooms. This study analyses prior use of Info-Sante CLSC telephone service by patients of emergency services. METHODS: Structured interviews were conducted with 850 patients of a general hospital emergency room and of walk-in medical clinics. Patients were recruited while waiting to see the physician between 8h and 23 h, 7 days a week, from November 1997 to June 1998. Information was collected on knowledge and use of the telephone-nursing triage service, health problem and perceived health status, information-seeking behaviour on health services, utilisation habits, social support, and socio-demographic characteristics. Interval estimates and multiple logistic regressions were performed. RESULTS: Of the patients who were aware of this service, 17,4% (CI(95)=0,14 - 0,20) had used it prior to their medical visit. Among these, 85,1% had received a recommendation to consult a doctor. Among the users who were at the hospital emergency room at the time of the study, 56,4% were advised to consult a walk-in clinic or a CLSC, 28,2% their family doctor and only 12,8% a hospital emergency room. The probability of prior recourse to the telephone nursing service is influenced significantly by the duration of the health problem (2-4 days versus<2 days: OR(adjusted)=2,03), new health problem (OR(adjusted)=1,98) and by the frequenting of walk-in clinics rather than hospital emergency rooms (OR(adjusted)=0,31). CONCLUSION: Despite a heightened awareness of the telephone-nursing triage service, few users of emergency services make use of it and, when they do, follow rather loosely the recommendation towards the type of service judged appropriate for their needs.

Adult↗
PubMed1997

NMR structural studies of human cystatin C dimers and monomers.

Human cystatin C undergoes dimerization before unfolding. Dimerization leads to a complete loss of its activity as a cysteine proteinase inhibitor. A similar process of dimerization has been observed in cells, and may be related to the amyloid formation seen for the L68Q variant of the protein. Dimerization is barrier controlled, and no dimer/monomer interconversion can be observed at physiological conditions. As a consequence, very stable, "trapped" dimers can be easily separated from monomers. A study of the structural aspects of cystatin C dimer formation was undertaken using NMR spectroscopy. The monomer/dimer model was verified by (pulse field gradient NMR) self-diffusion molecular mass measurements. Complete backbone resonance assignments and secondary structure determination were obtained for the monomer using data from triple resonance experiments performed on 13C/15N doubly labeled protein. A marked similarity of the cystatin C secondary structure to that of chicken cystatin was observed. Using uniformly and amino-acid-specific 15N-enriched protein, backbone NH signals were assigned for cystatin C in its dimeric state. Comparison of 1H -15N correlation NMR spectra of the monomer and dimer shows that the three-dimensional structure remains unchanged in the dimer and that only local perturbations occur. These are localized to the amino acid residues comprising the cysteine proteinase binding site. Such a mode of dimerization readily explains the complete loss of the inhibitory activity in the dimer. The NMR results also demonstrate that the dimer is symmetric.

Amino Acid Sequence↗
PubMed1994

Avian granulosa cell prostaglandin secretion is regulated by transforming growth factor alpha and beta and does not control plasminogen activator activity during follicular development.

The aim of the present study was to determine the role of transforming factor alpha (TGF alpha) and beta (TGF beta) in the regulation of prostaglandin (PG) secretion, and the relationships between PG and plasminogen activator (PA) activity in hen granulosa cells during ovarian follicular development. Cells from the first (F1), third (F3), and fifth and sixth (F5-6) largest preovulatory follicles were cultured for up to 21 h in the presence of TGF alpha (0.1-10 ng/ml) and/or TGF beta (4-20 ng/ml) or TGF alpha together with a cyclooxygenase inhibitor, indomethacin (0.05-0.5 microM). The release of PG into the incubation medium was determined by RIA. Cell-associated (PAc) and secreted (PAs) PA activities were measured by a fibrinolysis assay and characterized by zymography. Basal PGF secretion from F1, F3, and F5-6 cells was 2.2 +/- 0.3, 2.2 +/- 0.5, and 1.1 +/- 0.3 ng/micrograms DNA, respectively, and was higher than that of PGE. Basal total PA (PAc+PAs) activity from F1, F3, and F5-6 cells was 41 +/- 13,261 +/- 68, and 958 +/- 268 x 10(3) cpm/micrograms DNA, respectively. TGF alpha stimulated PG secretion and PA activity in a dose-dependent manner. The TGF alpha-induced PA activity was predominantly associated with a molecular mass of 30-35 kDa, corresponding to that of urokinase PA. The stimulation of PG secretion by TGF alpha was maximal in F3 and F1 granulosa cells whereas PA activity in the presence of TGF alpha was highest in cells from F5-6 follicles.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Interactions of transforming growth factor-alpha and -beta and luteinizing hormone in the regulation of plasminogen activator activity in avian granulosa cells during follicular development.

This study examined the influence of transforming growth factor-alpha (TGF alpha), TGF beta, and LH on progesterone (P4) secretion and plasminogen activator (PA) activity in cultured avian granulosa cells from the first (F1), third (F3), and fifth and sixth (F5-6) preovulatory follicles during a 21-h incubation period. PA activity in the cell (PAc) and the medium (PAm) fractions was measured by fibrinolysis and fibrin overlay methods. P4 was determined by RIA. Basal PAc and PAm activities were highest in cell cultures from the less mature (F5-6) follicles and decreased as follicles matured to the F1 stage of development. PAc activity was greater than PAm activity regardless of the stage of follicular maturation. TGF alpha (0.1-10 ng/ml) increased PA activity in cultures of granulosa cells from F1, F3, and F5-6 follicles in a concentration-dependent manner. TGF alpha-induced PAc and PAm activities were observed by 6 and 15 h of incubation, respectively, and increased rapidly between 15-21 h. LH (100 ng/ml) attenuated TGF alpha-induced PA activity by 15 h in cultures of granulosa cells from F1 and F3, but not F5-6, follicles. Basal PA activities were unaffected by the gonadotropin. TGF beta (2-100 ng/ml) stimulated PAc activity in a dose-dependent manner only in cultures of granulosa cells from F5-6 follicles and significantly enhanced TGF alpha-induced PAc and PAm activities in cell cultures from F3 and F5-6, but not F1, follicles. Basal and growth factor-induced PAc and PAm activities corresponded to a mol wt of about 35 kDa, a value consistent with that of the low mol wt uPA species. TGF alpha and TGF beta, alone or in combination, had no effect on basal P4 secretion at all stages of follicular development. TGF alpha, however, decreased LH-induced P4 secretion in F1 and F3 cultures. These results demonstrate a tightly controlled interaction of TGF alpha, TGF beta, and LH in regulating PA activity and P4 secretion during follicular development in the domestic hen.

Animals↗
PubMed1993

Influence of growth factors on the plasminogen activator activity of avian granulosa cells from follicles at different maturational stages of preovulatory development.

Granulosa cells from the first (F1), third (F3) and fifth and sixth (F5-6) preovulatory follicles and the small yellow follicles (SYFs; diameter 6-8 mm) were cultured for 21 h in the absence and presence of murine and human epidermal growth factors, fibroblast growth factor, transforming growth factors alpha and beta-I (TGF alpha, TGF beta), platelet-derived growth factor and insulin-like growth factor-I at concentrations of 0.1-100 ng/ml. Plasminogen activator (PA) activities in the cell (PAc) and in the medium (PAm) were measured by fibrinolysis and fibrin overlay methods. Basal PAc and PAm activities were highest in cell cultures from the less mature follicles (F5-6 and SYF) and decreased as the follicles matured (F3 > F1). PAc activity was greater than PAm activity, irrespective of the stage of follicular development. All growth factors examined at the 100 ng/ml level were effective in increasing PAc and PAm activities in cultures of granulosa cells from F1 follicles. However, only TGF alpha was able to increase PA activities at lower concentrations. The stimulation of the PA activities of granulosa cells from F3 follicles was inconsistent. None of the growth factors significantly increased PA activities in granulosa cells from F5-6 follicles and SYFs, as determined by fibrinolysis. The major PAc and PAm species (characterized by fibrin overlay) had a molecular mass of about 35 kDa, which is characteristic of the urokinase type. Both assay methods detected a stimulatory effect of the growth factors on PA activities in the granulosa cells from F1 follicles. However, an increase in PA activities in cells from F3 and F5-6 follicles and SYFs was indicated only after fibrin overlay analysis. Tritiated thymidine was incorporated into the DNA of granulosa cells at all stages of follicular development and was enhanced by all growth factors, although TGF alpha and TGF beta were the most effective and had a ranked order of activity: F3, F5-6 > F1, SYF. The present findings show that, of the growth factors examined, TGF alpha may be an effective regulator of PA activity in avian granulosa cells during follicular development, in addition to its observed mitogenic action.

Animals↗
PubMed1992

Role of arachidonic acid and its metabolites in the regulation of progesterone and oxytocin release from the bovine corpus luteum.

We have examined the effects of arachidonic acid (AA) and some of its metabolites on progesterone (P4) and oxytocin (OT) release by corpora lutea obtained from Holstein heifers at day 8 of the estrous cycle (Day 0 = estrus). The luteal cells were dispersed with collagenase and small and large cells were separated by unit gravity sedimentation and flow cytometry. After an 18-hr preincubation period, the cells were incubated in the presence of various treatments for 1 hr, followed by a 23-hr incubation period with no treatment. OT was secreted by the large, but not by the small, luteal cells into the incubation medium. AA elicited a significant (P less than 0.05) release of OT from the large cells and P4 from both the large and small cells within 1 hr of incubation, having a specific effect at a concentration of 10 microM. Larger doses (25 and 100 microM) of AA adversely affected the cell viability. Phospholipases A2 (0.5 unit/ml) and C (0.05 unit/ml) and calcium ionophore A23187 (0.1 microM) stimulated OT release from the large cells to the same extent as AA (10 microM). Inhibition of the AA cyclooxygenase metabolic pathway by indomethacin did not affect AA-induced release of OT and P4, although exogenous prostaglandins F2 alpha and I2 (5-25 ng/ml) stimulated the release of OT. Lipoxygenase products of AA (hydroxyeicosatetraenoic acid and leukotrienes; 25 ng/ml) also stimulated OT release. Inhibition of the lipoxygenase metabolic pathway by nordihydroguaiaretic acid abolished AA-induced release of both OT and P4. These results suggest that intracellular accumulation of free AA may modulate secretory functions in the bovine corpora lutea, including OT and P4 release.

Analysis of Variance↗
PubMed1990

Arginine vasopressin stimulation of prostaglandin F2 alpha release in heifers during the estrous cycle.

The effect of arginine vasopressin on the stimulation of prostaglandin F2 alpha (PGF2 alpha) release has been examined in vivo. Fifty-eight heifers received one intravenous injection of 10 IU arginine vasopressin on either Day 0 (n = 14), Day 6 (n = 12), Day 13 (n = 14) and Day 18 or 19 or 20 (Day 18-20, n = 18) after the onset of oestrus (Day 0) to determine the effect of arginine vasopressin at different times of the oestrous cycle. Frequent blood samples were taken before and after arginine vasopressin injection for the measurement of 13,14-dihydro-15-keto-PGF2 alpha (PGFM) by radioimmunoassay (RIA). Blood samples for progesterone determinations were taken 2 hr before and 24 hr after arginine vasopressin to monitor luteal function. The data show that arginine vasopressin causes an increase (P less than 0.005) in PGFM concentrations only at Day 18-20 of the cycle in 67% of the experimental heifers.

Animals↗
PubMed1989

Failure to maintain luteal function: a possible cause of early embryonic loss in a cow.

The effect of early pregnancy failure on the release of prostaglandin F2 alpha (PGF2 alpha) in response to oxytocin (Ot) was examined in an abnormal breeder (AB) heifer that was not able to maintain a pregnancy beyond 21 days. This animal was used in three experiments: 1) She received one intravenous injection of 100 IU Ot 17 days after the onset of oestrus (Day 0). Frequent blood samples were taken for the measurement of 15-keto-13,14-dihydro-PGF2 alpha (PGFM) by radioimmunoassay. Daily samples for progesterone (P4) determinations were taken to monitor luteal function. This was then repeated using the same animal at either day 17 or 18 or 19 (day 17-19) of pregnancy. 2) Embryos from superovulated normal breeder (NB) donors were transferred at day 7 to the AB heifer as well as to NB control animals. 3) Seven day old embryos from the superovulated AB heifer were transferred to NB recipient animals. At day 17-19 of pregnancy all the recipient heifers (experiments 2 and 3) were subjected to the same protocol as in experiment 1. The results showed that the ability of Ot to stimulate PGF2 alpha release was reduced in the NB recipients bearing viable embryos when compared to cyclic animals. However, for the AB heifer, Ot stimulated PGF2 alpha release to the same extent whether the animal was cyclic or pregnant. Furthermore, the AB animal did not have the extended luteal function associated with removal of viable embryos on day 17-19. The data suggest that the embryonic loss might have been caused by failure of the embryos to prevent the luteolytic release of PGF2 alpha.

Abortion, Veterinary↗
PubMed1988

Effect of the myorelaxant clenbuterol on the oxytocin-induced release of prostaglandin F2 alpha in ovariectomized heifers.

Clenbuterol, as other sympathomimetic drugs, relaxes the myometrium, thus causing a short-term inhibition of labor and the delay of parturition. This study has examined the influence of clenbuterol on the release of prostaglandin F2 alpha (PGF2 alpha) induced by oxytocin alone or with estradiol-17 beta. Five bilaterally ovariectomized heifers, primed with progesterone for 14 days, were used in two experiments. In the first they received two i.v. injections of oxytocin 6h apart, with and without an i.v. injection of clenbuterol before the second oxytocin injection; the second experiment was similar to the first except that the animals were given estradiol-17 beta 30 min after the first oxytocin injection. Frequent blood samples were taken for the measurement of 13,14-dihydro-15-keto-PGF2 alpha by radioimmunoassay. The data show that clenbuterol does not influence PGF2 alpha release in response to oxytocin alone or with estradiol-17 beta, and it does not inhibit the basal release of PGF2 alpha. This suggests that clenbuterol does not act on the endometrium to alter the secretion of PGF2 alpha in the non-pregnant cow.

Animals↗
PubMed1988

Patterns of improvement in spirometry, bronchial hyperresponsiveness, and specific IgE antibody levels after cessation of exposure in occupational asthma caused by snow-crab processing.

Thirty-one workers with occupational asthma caused by snow-crab processing were assessed by a long-term follow-up on three occasions at mean +/- SD intervals of 12.8 +/- 5.4, 31.4 +/- 6.3, and 64.4 +/- 6.3 months after leaving work. The diagnosis of work-related asthma was initially confirmed in all of them by specific inhalation challenges at the workplace or by laboratory inhalation of snow-crab boiling water (n = 24) or by serial monitoring of airway caliber and bronchial responsiveness to histamine at work and off work (n = 7). Total duration of work-related exposure was 12.8 +/- 5.6 months (range, 3 to 21 months), and the duration of symptoms after onset was 6.8 +/- 4.2 months (range, 1 to 18 months). At the time of diagnosis, all 31 subjects required medication for asthma, 11 had a FEV1 less than or equal to 85% predicted, and all subjects had a PC20 less than or equal to 16 mg/ml. Twelve of 25 serum samples assessed showed high levels of specific immunoglobulin E (IgE) antibodies to crab meat and/or boiling water. At the time of the first follow-up, there was a reduction in the number of subjects still requiring medication, with a significant reduction in FEV1, and a PC20 less than or equal to 16 mg/ml. However, no further change was observed afterwards. Similarly, the mean FEV1 and FEV1/FVC improved significantly from the time of diagnosis to the first follow-up (p less than 0.01), with a plateau thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Effects of progesterone and oestradiol-17 beta on oxytocin-induced release of prostaglandin F-2 alpha in heifers.

Seven bilaterally ovariectomized heifers were used in 4 experiments and received: (1) saline injections, as control; (2) one injection of oestradiol (3 mg; i.v.); (3) two i.v. injections of oxytocin (100 i.u.) 6 h apart; or (4) one oestradiol injection 30 min after the first oxytocin injection and a second oxytocin injection 6 h later. All experiments were performed without progesterone and then after 7, 14 and 21 days of progesterone treatment. Frequent blood samples were taken for 1 h before and 7 h after the first injection of oxytocin or oestradiol for the measurement of 13,14-dihydro-15-keto-PGF-2 alpha (PGFM) by radioimmunoassay. After 7, 14 and 21 days of progesterone priming, oestradiol caused a significant increase (P less than 0.001) in plasma PGFM after 6 h but not before. After 7, 14 and 21 days of progesterone, there was a significant increase (P less than 0.005) in PGFM after the first oxytocin injection and a similar increase following the second. The oxytocin-induced increase in PGFM after 14 and 21 days of progesterone was significantly higher (P less than 0.001) 6 h after oestradiol injection than before the oestradiol injection. There was no significant effect of oestradiol on the response to oxytocin in animals that received no progesterone or in those animals that received progesterone for only 7 days. These results show that, under the influence of progesterone, oestradiol enhances the oxytocin-induced release of PGF-2 alpha, and suggest a possible synergistic action of these hormones for the induction of luteolysis in heifers.

Animals↗
PubMed1985

Follow-up of occupational asthma caused by crab and various agents.

Sixty-three subjects with occupational asthma caused by crab (n = 31) and various other agents (n = 32) were studied after cessation of exposure at work for mean +/- SD intervals of 12.3 +/- 5.5 and 24.5 +/- 18.7 months (greater than 6 months in every subject), respectively. Nineteen of the subjects with asthma caused by crab and 30 of the subjects with asthma caused by various agents were still symptomatic of asthma, nine subjects of the latter group requiring bronchodilators (with inhaled beclomethasone in five) regularly. No significant changes in baseline spirometry were observed at the time of follow-up as compared with initial assessment, nine subjects (all in the asthma group caused by various agents) demonstrating significant bronchial obstruction. Improvement in bronchial responsiveness to histamine was significant (p less than 0.01) in the group with asthma caused by crab but not in the other group. Forty-eight of 52 subjects still had significant airway hyperexcitability. Subjects with asthma caused by crab who were asymptomatic and those subjects with asthma caused by various agents who used bronchodilators only if they were needed had worked for shorter intervals after onset of symptoms (p less than 0.01 and p less than 0.05, respectively). It is concluded that subjects with occupational asthma caused by various agents can remain symptomatic of asthma and demonstrate a persistence of bronchial obstruction and hyperexcitability for prolonged intervals after cessation of exposure.

Adult↗
PubMed1985

Effect of pregnancy on oxytocin-induced release of prostaglandin F2 alpha in heifers.

The effect of pregnancy on the release of prostaglandin F2 alpha (PGF2 alpha) in response to oxytocin (OT) has been examined. Fourteen cyclic heifers received one intravenous injection of 1 IU OT (n = 6) or 100 IU OT (n = 8) 17, 18, or 19 days (Day 17-19) after the onset of estrus (Day 0). Five of these animals also received 100 IU OT at Days 6 and 13 to determine the effect of OT at different times of the cycle. Frequent blood samples were taken for 60 min before and for 90 min after OT injection for the measurement of 15-keto-13,14-dihydro-PGF2 alpha (PGFM) by radioimmunoassay. The experiment was then repeated using the same animals at Day 17-19 of pregnancy (confirmed by the recovery of an embryo the day after OT injection). Following the injection of 1 IU OT, plasma PGFM reached its peak within 30 min with the increase significantly lower (P less than 0.05) in pregnant (1.13 +/- 0.10-fold) than in nonpregnant animals (2.07 +/- 0.27-fold). However, because only 3 of the 6 cyclic animals showed a response to 1 IU OT, the dose was increased to 100 IU in subsequent experiments. The animals that received 100 IU at Days 6 and 13 had no significant increase in PGFM concentrations (1.18 +/- 0.05-fold and 1.01 +/- 0.04-fold, respectively). At Day 17-19 the increase in plasma PGFM reached its peak 5-15 min after 100 IU OT and the increase was significantly greater in nonpregnant (3.23 +/- 0.17-fold) than in pregnant (1.21 +/- 0.02-fold; P = 0.003) heifers. Six of 11 animals injected at Day 17-19 of the cycle showed a decrease in progesterone (P4) the day after OT administration. These data show that the release of PGF2 alpha in response to OT is suppressed in pregnant animals in vivo, suggesting an antiluteolytic role for the embryo in luteostasis.

Animals↗
PubMed1984

Occupational asthma in snow crab-processing workers.

The prevalence of occupational asthma was studied in two snow crab-processing industries in operation since 1980. Before the 1982 season, all except 10 of the 313 employees were investigated by a questionnaire, prick skin tests with common allergens, crab n and crab-boiling water extracts, and spirometry. The diagnosis was confirmed in 46 (15.6%) workers (including 33 of 64 subjects with a history highly suggestive of occupational asthma in the previous seasons) by (1) specific inhalation challenges in 33 subjects (one immediate, nine dual, and 23 late asthmatic responses) and/or (2) a combination of monitoring of peak expiratory flow rates (n = 12) and significant changes in bronchial responsiveness to histamine (n = 16) as well as in spirometry (n = 18) after reappearance of symptoms on return to work. Positive skin tests to crab (p less than 0.001) and, to a lesser degree, smoking history (p = 0.03) but not atopy (p greater than 0.05) were related to the presence of occupational asthma. A high prevalence of rhinoconjunctivitis (35 of 46) and urticaria (16 of 46) was also documented in the affected individuals.

Asthma↗