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Biomedical subjects

S Meuris

Publications and source records attributed to S Meuris.

At least 55 records · Page 3Linked to original sources
PubMed1993

Protein and steroid levels in embryonic cavities in early human pregnancy.

Biochemical analysis including concentrations of urea, creatinine, human chorionic gonadotrophin (HCG), oestradiol, progesterone, and alpha-fetoprotein (AFP), two-dimensional gel electrophoresis, and the affinity of AFP for Concanavalin A (Con A)-Sepharose were performed on samples of exocoelomic and amniotic fluids retrieved by transvaginal puncture and maternal serum from 25 normal pregnancies between 5 and 12 weeks of gestation. Biochemical assays showed that during this period of gestation no differences in urea concentration were found between fluids from the three compartments, whereas creatinine concentration decreased significantly (P < 0.001) from maternal serum to amniotic fluid. The exocoelomic fluid contained significantly (P < 0.001) higher concentrations of oestradiol, progesterone and HCG than both maternal serum and amniotic fluid. AFP concentration was similar in amniotic and exocoelomic fluids and significantly (P < 0.001) lower in maternal serum. Between the second and the third months of gestation, urea concentration decreased significantly (P < 0.05) and oestradiol, HCG and AFP increased significantly in maternal serum (P < 0.05, P < 0.05, P < 0.001, respectively). During the same period of gestation, exocoelomic fluid concentrations of urea and HCG decreased significantly (P < 0.005, P < 0.001, respectively). Comparison of the two-dimensional gel patterns obtained from maternal serum with those from exocoelomic amniotic fluids revealed no significant qualitative differences, except for several small proteins. These results suggest that protein pathways across materno-embryonic membranes are not simply passive transfers.(ABSTRACT TRUNCATED AT 250 WORDS)

Amniotic Fluid↗
PubMed1993

Puberty in the male chimpanzee: time-related variations in circulating inhibin.

Circulating immunoreactive inhibin concentrations were determined in male chimpanzees (n = 12) during a 36-mo period starting 18 mo before the onset of pubertal testicular growth (Po). Serum levels of inhibin started to increase, together with LH and testosterone, 6 mo before a rise in FSH and Po. Before Po, inhibin was not related to gonadotropins but was related to testosterone levels (r = 0.263; p < 0.005; R2 = 7%). After Po, inhibin remained related to testosterone (r = 0.289, p < 0.01) but became inversely related to gonadotropins; FSH was the best predictor (r = -0.382, p < 0.0005; R2 = 30%) of this relationship. During the progressive rise in circulating inhibin, FSH increased and plateaued during 9 mo, then dropped to prepubertal levels. These findings suggest that a specific closed-loop negative feedback system for the secretion of FSH by inhibin is not functional before the onset of puberty in the chimpanzee. This feedback system seems to fully operate several months after the LH rise and may be related to the complete maturation of both Sertoli cells and spermatogenesis.

Animals↗
PubMed1993

Gestational malaria: assessment of its consequences on fetal growth.

In a region of Africa (Nord-Kivu, Zaire) where malaria is endemic, circulating malaria parasites, malaria-associated placental lesions, and a low hemoglobin level (< 10 g/dl) were observed, either singly or in combination, in 73.1% of women (n = 461) delivering at the maternity hospital. These pathologic findings were associated with low birthweight in 18.1% of the newborns, whereas the prevalence of low birthweight was 6.4% among cases without these findings (P < 0.05). Parasitemia was observed in 17.4% of all mothers and was associated with a significant decrease in birthweight. Malaria-associated lesions were found in 52.5% of all placentas and were associated with a decrease in birthweight, head circumference, and ponderal index of the newborns. Such lesions were more frequently observed among primiparae (60.5%) than among multiparae (49.5%; P < 0.05). Lastly, a low hemoglobin level, found in 38.6% of the mothers, was associated with a decrease in birthweight, length, and head circumference. The differences in the physical effects associated with each of the pathologic conditions suggest that parasitemia, placental lesions, and anemia result in acute, subacute, and chronic impairment of fetal growth, respectively. Moreover, their deleterious effects may be cumulative, since the most dramatically affected physical patterns were found when the pathologic findings were associated in the same patient. Frequent antenatal monitoring of maternal hemoglobin and parasitemia, accompanied, when necessary, with curative treatments, may help to reduce the prevalence of intrauterine growth retardation and its procession of perinatal complications.

Anthropometry↗
PubMed1992

Influence of human chorionic gonadotrophin, oestradiol and progesterone on uteroplacental and corpus luteum blood flow in normal early pregnancy.

A transvaginal colour and pulsed Doppler study was performed on 44 women with normal pregnancies between 5 and 16 weeks of gestation. Maternal levels of human chorionic gonadotrophin (HCG), free alpha-HCG subunit, free beta-HCG subunit, 17 beta-oestradiol and progesterone were determined in sera obtained at the time of Doppler examination. Uterine peak systolic velocity (PSV) and alpha-HCG and 17 beta-oestradiol levels increased significantly (P < 0.001) from the second to the fourth month of gestation, whereas uterine and spiral resistance index (RI) decreased significantly (P < 0.005 and P < 0.001, respectively) with gestational age. Levels of HCG and beta-HCG peaked significantly (P < 0.01) during the third month of gestation. Corpus luteum PSV and RI and progesterone levels did not vary significantly with gestational age. Multiple regression analysis showed that gestational age was the only significant (P < 0.05) contributor to uterine PSV and spiral RI variability. In addition to gestational age, 17 beta-oestradiol had a significant (P < 0.001) influence on uterine RI. Both corpus luteum PSV and RI were significantly (P < 0.01 and P < 0.05, respectively) related to progesterone levels. Corpus luteum PSV was also significantly (P < 0.05) related to 17 beta-oestradiol levels and RI to HCG levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1991

Puberty in the male chimpanzee: progressive maturation of semen characteristics.

Cellular and biochemical characteristics of semen obtained by masturbation were studied in 5 pubertal chimpanzees during 1.5 yr. The dental age corresponding to the beginning of the pubertal testicular growth (Po) ranged from 5.0 to 8.3 years (mean = 6.7 +/- 1.2 yr). Time-related variations of all studied parameters were analyzed according to Po and, therefore, independently of the dental age. The emission of first ejaculates, and therefore the onset of activity of the accessory sex gland, was estimated to occur 4 mo after Po. The ejaculate volume (n = 132, r = 0.704, p less than 0.001), as well as the total amounts of l-carnitine (n = 65, r = 0.649, p less than 0.001), fructose (r = 0.522, p less than 0.001), citrate (r = 0.748, p less than 0.001), and acid phosphatase (r = 0.756, p less than 0.001) increased with time. First-obtained ejaculates contained no spermatozoa. Spermarche was estimated to occur 9.4 mo after Po. Total sperm count increased with time (r = 0.595, p less than 0.001). The motility and viability of spermatozoa increased with time (r = 0.474, p less than 0.01 and r = 0.632, p less than 0.001, respectively) while their morphology did not vary. The volume of the liquefied fraction and its content in free spermatozoa considered as available for fecundation remained low until the end of the study, most likely because of a delayed maturation of the prostate. This study shows that the maturation of the male genital tract is a progressive process. (ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Puberty in the male chimpanzee: time-related variations in luteinizing hormone, follicle-stimulating hormone, and testosterone.

The onset of pubertal testicular growth (Po) occurred in 12 out of 20 male chimpanzees surveyed monthly for at least 3.7 yr. When animals were synchronized according to Po, the mean weight gain was found to be higher before than after Po, and testicular volume started to rise immediately after Po. The earlier significant hormonal events were a rapid rise in LH and a slight testosterone increase occurring 6 mo before Po. Thereafter, the levels of LH remained elevated while testosterone continued to rise in parallel with the testicular volume. FSH levels increased suddenly at Po, 6 mo after the LH increase. FSH remained elevated for only 9 mo, then dropped to prepubertal levels. The dissociation between onsets of pubertal increases in LH and FSH secretions suggests that the complete reawakening of the hypothalamic-pituitary unit lasts several months. The secondary drop of FSH, occurring at the time of spermarche, may be induced by factor(s) secreted by the testis.

Animals↗
PubMed1989

Influence of ejaculation frequency on semen characteristics in chimpanzees (Pan troglodytes).

Semen samples were obtained by masturbation from 6 chimpanzees and the spontaneously liquefied fraction and the remaining coagulum were studied separately. When semen was collected once or twice a week, large intra-individual variations were observed for all measures. The liquefied fraction represented 26.5 +/- 3.2% (weighted mean +/- s.d.) of the total ejaculate but contained 51.3 +/- 3.8% of all emitted spermatozoa. Fructose concentration was higher in the coagulum than in the liquefied fraction (29.3 +/- 3.0 mumol/ml vs 12.0 +/- 2.7 mumol/ml, P less than 0.001) whereas acid phosphatase was less concentrated in the coagulum than in the liquefied fraction (3.5 +/- 0.3 x 10(3) IU/ml vs 13.0 +/- 0.9 x 10(3) IU/ml, P less than 0.001). L-Carnitine and citrate concentrations did not differ between the two fractions of the ejaculate. When semen collection was repeated every hour for 5 h, the ejaculate volume increased from 2.6 +/- 0.7 to 4.7 +/- 0.6 ml (P less than 0.001), whereas total sperm count decreased from 1278 +/- 872 x 10(6) to 587 +/- 329 x 10(6) (P less than 0.05) between the 1st and the 6th ejaculate. In the spontaneously liquefied fraction, the sperm count decreased from 984 to 369 x 10(6). The 6 successive ejaculates gave a total of 20.2 +/- 7.6 ml and 4278 +/- 2884 x 10(6) spermatozoa. The increase of the ejaculate volume was essentially due to an increase of the volume of the coagulum which closely correlated with total amount of fructose (from seminal vesicles) (r = 0.913, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Cellular and biochemical characteristics of semen obtained from pubertal chimpanzees by masturbation.

Semen characteristics were studied in 6 wild-born chimpanzees with dental ages ranging approximately from 6 to 12 years. The animals formed 2 groups, early pubertal (EP, N = 3, 6-9 years) and late pubertal (LP, N = 3, 11-12 years). Mean body weight, testicular volume and serum androgen concentration were significantly lower in Group EP (32.2 +/- 1.6 kg, 34.0 +/- 7.7 cm3, 2.1 +/- 0.1 ng/ml) than in Group LP (55.7 +/- 5.7 kg, P less than 0.01; 100.5 +/- 11.9 cm3, P less than 0.01; 3.6 +/- 0.7 ng/ml, P less than 0.05). Ejaculates were obtained by masturbation in all subjects. The mean ejaculate volume was lower in Group EP (0.56 +/- 0.20 ml) than in Group LP (3.77 +/- 0.73 ml, P less than 0.01). In Group EP, 2 animals were azoospermic while the third produced semen with means of 57.1 x 10(6) spermatozoa per ml, 20% motility and 40% vitality. These values were low when compared with the mean values of Group LP (376 x 10(6) spermatozoa per ml, 67% motility and 78% vitality). Mean total sperm count was correlated with testicular volume (r = 0.84) and serum androgen concentration (r = 0.96). The mean concentrations of L-carnitine, fructose, citrate and acid phosphatase for the two groups were not significantly different; but, related to the differences in ejaculate volumes, their total amounts in total ejaculate were lower in Group EP than in Group LP. These results suggest that, in chimpanzees, mechanisms of seminal plasma production and ejaculation are functional early in the reproductive life and that the emission of spermatozoa occurs later.

Acid Phosphatase↗
PubMed1986

[Malaria: the end of a multimillenia reign?].

Malaria is one of the oldest and more pervasive diseases of mankind with half of the world's population still meeting with Plasmodium. The resistance of the parasite and its carrier, anopheles, at the current levels of antimalaria programs results in recurrence of this illness among the less developed tropical zones. The high risk groups for malaria are pregnant women and children, resulting in a delay of intra-uterine growth, neonatal/infantile morbidity and mortality. Recent progress in molecular biology provide new perspectives for preventive and curative solutions, more specifically in the relationship between host and parasite.

Female↗
PubMed1985

Rapid electrotransfer of proteins from polyacrylamide gel to nitrocellulose membrane using surface-conductive glass as anode.

A new type of inexpensive horizontal apparatus for the electrophoretic transfer of proteins from a gel to an immobilization membrane has been developed. In this system, gel and membrane were directly pressed between two flat electrodes. A surface-conductive glass was used as anode and a stainless-steel plate as cathode. Proteins could be transferred from polyacrylamide gel to nitrocellulose sheet, with a yield of at least 90% in 60-90 min, without overheating, using a voltage gradient of 30-40 V/cm. Moderate volumes of separate anodic (with 20% methanol) and cathodic (with 0.1% sodium dodecyl sulfate) buffers were suited for optimal transfer of proteins with relative molecular mass (Mr) in the 14,000-94,000 range.

Animals↗
PubMed1985

Presence of helodermin-like peptides of the VIP-secretin family in mammalian salivary glands and saliva.

Helodermin is a biologically active peptide isolated from the venom of the Gila monster lizard (Heloderma suspectum) whose structure is related to that of vasoactive intestinal peptide and secretin. Using a specific radioimmunoassay based on antisera prepared by immunizing rabbits with natural helodermin, we demonstrated the presence of helodermin-like material in mammalian salivary glands, including parotid, submaxillary and sublingual glands from rat and dog, and parotid and submaxillary glands from man. All helodermin-like materials had an apparent molecular mass of 4-12 kDa. Dog saliva, collected after pilocarpine stimulation, revealed similar immunoreactivity with a major component around 6 kDa.

Amino Acid Sequence↗
PubMed1984

Cleaving of disulfide bridges and apparent molecular weight of human prolactin variants as revealed by immunoperoxidase electrophoresis.

Five highly purified preparations of human pituitary prolactin, widely used in radioimmunoassays, were analyzed by immunoperoxidase electrophoresis with rabbit antisera raised against ovine and rat prolactin. When unreduced, the prolactin content of these preparations was separated into one major prolactin-like immunoreactive band of Mr 23,000, and four fainter immunoreactive bands of Mr's 16,000, 22,000, 25,000, and 45,000. Increasing the 2-mercaptoethanol concentration modified the relative proportions and the Mr of immunoreactive bands so that, after extensive reduction, only two immunoreactive bands were separated, one major band of Mr 25,000 and one fainter band of Mr 17,000. A direct relationship existed between the load of prolactin submitted to electrophoresis in the 0.25 to 75 ng range and the optical density of the separated bands.

Animals↗
PubMed1983

Monomeric pituitary growth hormone and prolactin variants in man characterized by immunoperoxidase electrophoresis.

Immunoperoxidase electrophoresis, combining SDS--ME--PAGE and the 'double bridge' immunoperoxidase staining was applied to crude human pituitary homogenates. With anti-hGH and anti-hPL sera, 4 hGH-related monomers were characterized: a Mr 22 000 peptide corresponding to hGH; a Mr 20 000 peptide corresponding to the known hGH variant and two unknown hGH variants (Mr 65 000 and Mr 75 000). With anti-ovine, rat and human PRL sera, 4 PRL-related monomers were immunostained: one comigrated with purified hPRL (Mr 25 000), and 3 were unknown (Mr 29 000; Mr 45 000; Mr 16 000).

Aged↗
PubMed1983

Immunocytochemical localization of prolactin-like immunoreactivity in rat pancreatic islets.

Animal experiments and clinical data indicate that prolactin (PRL) induces hyperinsulinemia and even diabetes. The effects of PRL on carbohydrate metabolism may be explained by at least two different mechanisms. Either PRL induces an insulin resistance at the peripheral tissue level, or PRL has a direct cytotropic effect on the pancreatic islets. Obviously, both mechanisms inducing hyperinsulinemia may coexist. We report here immunocytochemical evidence that PRL is localized in the endocrine pancreas of the normal adult rat. More precisely, the immunoreactive PRL is distributed in the cytoplasm of insulin-secreting B cells. These findings support a direct action of PRL on the endocrine pancreas.

Animals↗
PubMed1980

Immunoenzymatic localization of prolactin-like immunoreactivity in decidual cells of the endometrium from pregnant and nonpregnant women.

Prolactin-like immunoreactivity has been localized by an immunoenzymatic method in the decidual cells of the endometrium in cases of early (10 weeks) normal pregnancy, (12 weeks) molar pregnancy, (8--10 weeks) tubal pregnancy, and of a nonpregnant woman under progestogen (lynestrenol) treatment. A specific endocrine influence, predominantly progestogenic, rather than the implantation of trophoblastic tissue seems to be required for the appearance of prolactin-like immunoreactivity in the decidual cells of the endometrium.

Endometrium↗