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Biomedical subjects

C Gagnon

Publications and source records attributed to C Gagnon.

At least 73 records · Page 4Linked to original sources
PubMed1995

Effect of adding the D-1 agonist CY 208-243 to chronic bromocriptine treatment of MPTP-monkeys: regional changes of brain dopamine receptors.

1. Eleven monkeys were administered N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP): eight were treated with bromocriptine for one week and then CY 208-243 (four monkeys) or saline (four monkeys) was added to the bromocriptine treatment. 2. Addition of CY 208-243 increased the therapeutic response observed with the ergot alone without inducing dyskinesia. 3. Following MPTP, [3H]-SCH 23390 specific binding to D-1 receptors as well as [3H]-spiperone and [3H]-N-n-propylnorapomorphine specific binding to D-2 receptors increased in posterior striatum compared to control animals, whereas [3H]-SKF 38393 binding to D-1 receptors tended to decrease. 4. Dopamine receptor density was unchanged in anterior striatum of untreated MPTP-monkeys. 5. In the posterior striatum, both dopaminergic treatments decreased towards control values [3H]-SCH 23390, [3H]-spiperone and [3H]-N-n-propylnorapomorphine binding whereas they did not significantly change [3H]-SKF 38393 specific binding. [3H]-SKF 38393 specific binding increased in anterior striatum of bromocriptine-treated MPTP-monkeys, compared to untreated MPTP-animals, and this increase was abolished in animals treated with bromocriptine+CY 208-243. 6. The present study shows that in MPTP-monkeys, treated or not with DA agonists, the D1 and D2 receptor changes are concentrated in the posterior striatum and that denervation appears to cause a shift from the high to the low affinity agonist state of D1 receptors but not for the D2 subtype.

Animals↗
PubMed1995

Capacitation-associated production of superoxide anion by human spermatozoa.

Previous results demonstrating the role of the superoxide anion in human sperm capacitation indirectly suggest that the superoxide anion is not only essential to this process, but is also generated by spermatozoa themselves. Our aim was to provide direct evidence for production of superoxide anion by capacitating spermatozoa. Three chemiluminescence probes were tested to detect the superoxide anion. Luminol- and lucigenin-amplified chemiluminescence of capacitating spermatozoa did not differ from that of background level. However, significant SOD-inhibitable chemiluminescence was observed when the Cypridina luciferin analog, MCLA, was used as probe. The chemiluminescence associated to capacitation of spermatozoa incubated in Ham's F-10 supplemented with fetal cord serum ultrafiltrate was 1270 +/- 77 mV/10 s (with 8 x 10(6) cells/ml; n = 37), and corresponded to levels of sperm hyperactivation (12 +/- 1%) and capacitation (17 +/- 2%) that were significantly different from those of control spermatozoa (4.9 +/- 0.8% and 6 +/- 1%, respectively). MCLA was cell impermeant and superoxide specific. The level of capacitation-associated chemiluminescence was directly related to sperm concentration up to 30 x 10(6) cells/ml. Sperm production of superoxide anion started at the beginning of incubation in capacitating conditions and was sustained over more than 4 h. This is the first direct evidence for the generation, by human spermatozoa, of a sustained level of superoxide anion that is associated with the progressive development of hyperactivation and capacitation.

Humans↗
PubMed1995

Impact of reactive oxygen species on spermatozoa: a balancing act between beneficial and detrimental effects.

Reactive oxygen species (ROS) have beneficial or detrimental effects on sperm functions depending on the nature and the concentration of the ROS involved, as well as the moment and the location of exposure. Excessive generation of ROS in semen, mainly by neutrophils but also by abnormal spermatozoa, could be a cause for infertility. Hydrogen peroxide is the primary toxic ROS for human spermatozoa. Low concentrations of this ROS do not affect sperm viability but cause sperm immobilization mostly via depletion of intracellular ATP and the subsequent decrease in the phosphorylation of axonemal proteins. High concentrations of hydrogen peroxide induce lipid peroxidation and result in cell death. On the other hand, the superoxide anion appears to play a major role in the development of hyperactivation and capacitation. The observations that: (i) exogenously generated superoxide anions induce hyperactivation and capacitation; (ii) capacitating spermatozoa themselves produce elevated concentrations of superoxide anion over prolonged periods of time; and (iii) removal of this ROS by superoxide dismutase prevents sperm hyperactivation and capacitation induced by various biological fluids, stress the importance of the superoxide anion in these processes.

Animals↗
PubMed1995

Sperm motility inhibitor from human seminal plasma: association with semen coagulum.

Human seminal plasma contains a sperm motility inhibitor (SPMI) originating from the seminal vesicles as a 52 kDa precursor form that is rapidly degraded by prostatic proteases after ejaculation. In this study, the distribution of SPMI biological activity and antigens was analysed in chemically induced, as well as naturally occurring, arrest of semen liquefaction. SPMI activity was detected exclusively in the coagulated semen fraction at 2200 +/- 560 IU, whereas total seminal plasma proteins separated more evenly between soluble and coagulated components (91 +/- 19 and 65 +/- 18 mg, respectively). An SPMI antiserum recognized different forms of SPMI precursors at 52, 38, 35, 33 and 20 kDa in the coagulum while the soluble protein fraction contained only one major immunoreactive band at 15 kDa. High levels of SPMI activity (1500 +/- 180 IU/ml) together with high molecular mass forms of SPMI precursor and low sperm motility (26%) were detected in semen samples that failed to liquefy spontaneously at room temperature. Addition of prostatic secretions to the non-liquefying samples caused a decrease of SPMI activity (330 +/- 17 IU/ml) and transformed the SPMI precursor into low molecular mass forms (14-22 kDa) with a concomitant increase in sperm motility to 49%. The results suggest that SPMI is highly associated with the seminal coagulum components as very active forms that may adversely affect sperm motility when not properly processed after ejaculation.

Adult↗
PubMed1995

A rapid PCR-based test for the endogenous viral element ev3 of chickens.

A short fragment of chicken genomic DNA encompassing the insertion site of the endogenous avian leucosis viral element ev3 was isolated using the inverse polymerase chain reaction (inverse PCR) technique. The nucleotide sequence of the unoccupied site was used to design PCR primers that can be used to unambiguously determine the genetic status of any chicken, with respect to ev3. Screening of a small number of individuals from exotic breeds of chickens suggested that the frequency of ev3 is highly variable. The ev3 integration site shows a high degree of sequence homology with the macrophage-specific tyrosine kinase gene, bmk, in mice.

Animals↗
PubMed1995

Diabetes mellitus increases nitric oxide synthase in penises but not in major pelvic ganglia of rats.

OBJECTIVE: To determine the effect of diabetes mellitus (DM) on erectile function and evaluate the levels of nitric oxide synthetase (NOS) activity in streptozotocin-induced diabetic rats. MATERIALS AND METHODS: Rats were studied at 9 weeks and 14 weeks after the induction of DM by streptozotocin and compared with untreated control rats. Erectile potency was assessed physiologically by testing and recording mating behaviour. NOS activity was assayed in penile tissues and major pelvic ganglia (MPG) by conversion of [3H] L-arginine to [3H] citrulline. Histological, ultrastructural and immunohistochemical studies of penile tissues were performed in similar groups of rats. RESULTS: Diabetes mellitus adversely and significantly degraded all parameters of mating behaviour, thus indicating defective erectile potency. However, NOS activities in penile tissues from both groups of diabetic rats were significantly higher than those in controls (P < 0.01). In MPG, NOS activities were not significantly different between diabetic and control rats (P > 0.05). Histological, ultrastructural and immunohistochemical studies of penile tissues revealed no significant differences between control and diabetic rats, indicating an intact effector organ (smooth muscles) in rats with up to 14 weeks of DM. CONCLUSION: The impotence frequently observed in diabetic subjects would suggest that despite the increase in NOS activity in the penis, the pharmacological action of nitric oxide is impaired.

Amino Acid Oxidoreductases↗
PubMed1995

Teacher ratings of children's behaviors and teachers' management styles: a research note.

The purpose of this study was to explore how changes in teacher ratings of children's behavior problems from kindergarten to first grade might vary with teachers' styles of managing behavior problems. Familial and socioeconomical variables were controlled because of their potential modulating effects. Subjects were from a community sample of 1,573 boys and girls rated by teachers, mothers and peers (for one part of the sample) on aggressiveness-hyperactivity, anxiety-withdrawal and social skills deficits. Teacher ratings of aggressive-hyperactive behaviors significantly changed from kindergarten to grade one when the teachers had different management styles. Mother and peer ratings, however, did not change. The importance of considering teachers' management styles when assessing behavior problems in school is stressed.

Aggression↗
PubMed1995

The proportions of G gamma- and A gamma-globins in the fetal hemoglobin synthesized in preterm and term infants.

The change in G gamma to A gamma ratio in relation to the switchover of fetal HB (HbF) to adult Hb (alpha 2 beta 2) synthesis has not been well defined. The gamma-globins of HbF (alpha 2 gamma 2) have either glycine (G gamma) or alanine (A gamma) at position 136. During fetal life the G gamma makes up 70% of the gamma-globins, although they are 40% of the small amounts of HbF in the adult. To further the understanding of this switchover, globin chain synthesis was determined sequentially in eight preterm and 20 full-term infants postnatally. To complete the study, single analysis was also carried out in eight term infants at birth and six preterm infants at the postconceptional age equivalent to term. Blood samples were incubated in an amino acid mixture containing 3H-leucine and subjected to reversed-phase liquid chromatography. The results demonstrated that the fetal proportions of G gamma to A gamma are rigidly controlled according to postconceptional age and not affected by postnatal age after preterm birth. During the early postconceptional age switchover from HbF to adult Hb synthesis, an equal repression of the G gamma and A gamma chains was found. However, based on the values obtained from the term infants, after a postconceptional age of 44 wk, the levels of G gamma to total gamma synthesis begin to decrease and become more variable.

Fetal Hemoglobin↗
PubMed1995

Influence of the alv6 recombinant avian leukosis virus transgene on production traits and infection with avian tumor viruses in chickens.

The biological costs of the alv6 recombinant transgene that in chickens induces dominant resistance to the subgroup A avian leukosis virus (ALV), in terms of effects on production traits, were studied. Four generations of White Leghorn chickens of Line TR, segregating for alv6 but free of endogenous viral genes, as well as two generations of crosses between TR and Ottawa Line WG (WGTR) were tested under a specific-pathogen-free environment. In the birds studied, the transgene appeared unchanged compared to the original alv6: No major changes in alv6 DNA were detected by restriction analysis, the transgene did not express the group-specific antigen of ALV, and its presence was associated with absence of immune response to ALV. In most test years, and both TR and WGTR genomic backgrounds, alv6 was associated with delayed sexual maturity by 4 to 6 d, reduced egg production to 497 d of age by 20 to 46 eggs, and a 3.6 to 15% decline in egg production rate. No consistent effects on other traits, including mortality, were detected. When inoculated with the AC-1 isolate of Marek's disease virus in a separate experiment, TR birds with alv6 had a significantly lower body weight gain to 10 d of age than their sibs without the transgene. Thus, transgenesis has biological costs that have to be assessed against desirable effects of transgenes.

Animals↗
PubMed1995

Increased reactive oxygen species formation in semen of patients with spinal cord injury.

OBJECTIVES: To evaluate reactive oxygen species production of semen samples and Percoll-washed spermatozoa from men with spinal cord injuries and to determine if there is a relationship between this reactive oxygen species production and sperm motility. PARTICIPANTS: Semen samples from healthy volunteers and infertile patients were collected by masturbation. INTERVENTIONS: Semen samples from men with a spinal cord injury were obtained by electroejaculation or by masturbation after treatment with physostigmine. MAIN OUTCOME MEASUREMENTS: Motility was measured using the CellSoft computer-assisted analysis system (Cryo Resources Ltd., Montgomery, NY). Luminol-amplified chemiluminescence was used to measure reactive oxygen species production. RESULTS: Semen samples and Percoll-washed spermatozoa from men with a spinal cord injury produced reactive oxygen species at much higher frequency and levels than equivalent preparations from infertile men or healthy volunteers. There was an inverse relationship between the percentage of motility and reactive oxygen species production in Percoll-washed spermatozoa from men with a spinal cord injury. CONCLUSION: Semen samples and Percoll-washed spermatozoa from men with spinal cord injury produce high levels of reactive oxygen species that may be related to the low sperm motility and infertility observed in these men.

Adult↗
PubMed1994

Cloning and tissue expression of bovine follistatin cDNA.

Bovine follistatin cDNA sequences were derived using a cloning strategy based entirely on reverse transcription and polymerase chain reaction amplification of RNA derived from bovine ovarian and testicular tissues. Complete bovine follistatin cDNA coding sequences are presented including 1,029 bases of open reading frame, the 5' translational start codon, and the 3' translational stop codon. Homologies of bovine follistatin cDNA with pig, human, rat, and partial sheep sequences are 94.3%, 92.4%, 89.9%, and 98.4% at the nucleic acid level and 98.3%, 97.1%, 95.6%, and 100% at the deduced amino acid level, respectively. Northern blot analysis on a survey of bovine reproductive tissues showed strongest expression in ovaries collected from superovulated cows and major RNA species at 2.8 Kb and 1.75 Kb.

Amino Acid Sequence↗
PubMed1994

Reactive oxygen species released by activated neutrophils, but not by deficient spermatozoa, are sufficient to affect normal sperm motility.

OBJECTIVES: To determine whether reactive oxygen species (ROS) produced by abnormal or deficient spermatozoa and polymorphonuclear leukocytes (PMN, activated or not) can affect normal sperm motility. To determine what level of ROS is detrimental to spermatozoa. SUBJECTS: Patients consulting the Infertility Clinic at the Royal Victoria Hospital and healthy volunteers. METHODS: Normal spermatozoa (not producing ROS) were incubated with ROS-producing spermatozoa or PMN (activated or not), and motility was analyzed using a computer-aided sperm analysis system. The proportion of ROS produced by spermatozoa and released extracellularly was estimated by the decrease in the chemiluminescence observed in the presence of catalase and superoxide dismutase. RESULTS: There was no consistent effect on motility when ROS-producing and non-ROS-producing spermatozoa were mixed. This lack of effect could be due to the relatively low level of ROS produced by spermatozoa as well as the fact that only a third of these ROS are released outside spermatozoa. To cause a low but significant decrease (15 +/- 4%) in sperm motility after a 5-hour incubation, the level of ROS imposed on spermatozoa must be equivalent to ROS released by 1 x 10(6) activated PMN/mL. CONCLUSIONS: The production of ROS by deficient spermatozoa is low and of no consequence to the motility of normal spermatozoa present in the same sperm preparation. However, 1 x 10(6) activated PMN/mL, with a 1,000-fold higher ROS production, have detrimental effects on the motility of normal washed spermatozoa.

Extracellular Space↗
PubMed1994

Hypoxemia and increased fetal hemoglobin synthesis.

Fetal hemoglobin (HbF) synthesis in children with congenital cyanotic heart disease was compared that in normal children. Children with hypoxemia had higher levels of hemoglobin, total HbF, and HbF synthesis. In these children there was also an inverse correlation between HbF synthesis and oxygen content, as well as between HbF synthesis and hemoglobin concentration. Thus hypoxemia increases HbF synthesis.

Child↗
PubMed1994

A monoclonal antibody against the dynein IC1 peptide of sea urchin spermatozoa inhibits the motility of sea urchin, dinoflagellate, and human flagellar axonemes.

To investigate the role of axonemal components in the mechanics and regulation of flagellar movement, we have generated a series of monoclonal antibodies (mAb) against sea urchin (Lytechinus pictus) sperm axonemal proteins, selected for their ability to inhibit the motility of demembranated sperm models. One of these antibodies, mAb D1, recognizes an antigen of 142 kDa on blots of sea urchin axonemal proteins and of purified outer arm dynein, suggesting that it acts by binding to the heaviest intermediate chain (IC1) of the dynein arm. mAb D1 blocks the motility of demembranated sea urchin spermatozoa by modifying the beating amplitude and shear angle without affecting the ATPase activity of purified dynein or of demembranated immotile spermatozoa. Furthermore, mAb D1 had only a marginal effect on the velocity of sliding microtubules in trypsin-treated axonemes. This antibody was also capable of inhibiting the motility of flagella of Oxyrrhis marina, a primitive dinoflagellate, and those of demembranated human spermatozoa. Localization of the antigen recognized by mAb D1 by immunofluorescence reveals its presence on the axonemes of flagella from sea urchin spermatozoa and O. marina but not on the cortical microtubule network of the dinoflagellate. These results are consistent with a dynamic role for the dynein intermediate chain IC1 in the bending and/or wave propagation of flagellar axonemes.

Adenosine Triphosphatases↗
PubMed1994

Human sperm-zona pellucida interaction is inhibited by an antiserum against a hamster sperm protein.

During epididymal transit, mammalian spermatozoa acquire new surface antigens that may participate in gamete interaction. We have previously described a 26-kDa (P26h) epididymal hamster sperm protein that we propose to be involved in fertilization. In this study, we have searched for an antigenically related protein in the human, and have found that an anti-P26h antiserum recognizes a 34-kDa (P34H) protein on Western blot of human sperm proteins. Immunostaining showed that this protein is localized on the acrosomal cap of human epididymal spermatozoa but not on testicular gametes. The effect of the anti-P26h antiserum on the fertilizing ability of human spermatozoa was evaluated by use of a human zona pellucida binding assay. Compared to the preimmune serum, the antiserum caused a highly significant decrease in the number of sperm bound per zona pellucida. This inhibition was not due to the induction of a premature acrosomal reaction nor to an effect on the motility of the spermatozoa. The antiserum recognizing the P34H human sperm protein had no effect on gamete fusion as determined by the zona-free hamster test. Our results suggest that the human spermatozoon acquires an epididymal protein that shares a common epitope(s) with the P26h hamster sperm protein. The possible involvement of this human sperm antigen in the binding to the zona pellucida is discussed.

Acrosome↗