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At least 181 records · Page 10Linked to original sources
PubMed1985

Interindividual phenotypic variations in CLL B lymphocyte maturation indication of different maturation blocks.

Peripheral blood lymphocytes from 8 patients with B-derived chronic lymphocytic leukaemia were stimulated by Staphylococcus aureus bacteria strain Cowan 1 with T cell mitogens PHA or PWM in 5-7 day suspension cultures. For the first group of patients proliferation and maturation tests were performed on T cell enriched and T cell depleted subpopulations, obtained from harvested lymphocytes at the end of cultures by the sheep red cell rosette technique. To re-examine mutual influences of cultivated T and B cells in the second group of experiments, lymphocytes from CLL patients and from 5 healthy individuals were investigated by the use of transmembrane cocultivation system after Feldman and Basten. The proliferative responses to lectin and to bacteria were assessed by 3HTdR-blastic and mitotic indices. The maturation process of B lymphocytes was examined by cytoplasmic Ig, studied by FITC-conjugated antisera. Results obtained with cocultivation system support the view that T cell replacing factor(s) were required for inducing prolonged growth and development of maturation of more numerous B lymphocytes in response to Staphylococcus aureus, a T cell independent, B specific polyclonal stimulator. Results analysed in different patients indicate various degrees of maturation of B cells including their differentiation towards a plasmacytoid cell, accompanied by various proliferative capacities of B and T lymphocytes. This functional analysis reflects the heterogeneity of B-CLL patients group.

Adult↗
PubMed1975

[Modulation of 17-alpha-hydroxy-20 beta-dihydroprogesterone or gonadotropic extract activity on the in vitro intrafollicular maturation of rainbow trout (Salmo gairdnerii) oocytes by various steroids lacking maturing activity].

The efficiency of 17 alpha-hydroxy-20 beta-dihydroprogesterone (17 alpha-20 beta Pg) or of a Trout pituitary gonadotropic extract to induce intrafollicular maturation of trout oocytes can be modulated by some steroids which do not present any direct maturing action: gonadotropic extract efficiency is lowered by estradiol and estrone, and enhanced by testosteron. As these steroids do not present a significant effect on 17 alpha-20 beta Pg induced maturation, their site of action may be located in the follicular tissues. The corticosteroids, particularly cortisol and cortisone enhance the maturing efficiency of gonadotropin and stimulate much more strongly the efficiency of 17 alpha-20 beta Pg. This suggests a direct effect on oocyte sensitivity to 17 alpha-20 beta Pg.

20-alpha-Dihydroprogesterone↗
PubMed1993

Determination of maturity at birth: further observations on a maturity scoring system for head circumference and mid-arm circumference.

Over a 3-month period, 114 infants were analysed to establish the reliability and usefulness of the maturity scoring for mid-arm circumference (MAC) and head circumference using the Dubowitz system as standard. Total maturity scores of the two methods showed highly significant correlation with gestational age. There was also a highly significant correlation between total maturity scores of both methods. The usefulness of the model was suggested by its comparable accuracy to the Dubowitz system. The model, however, was a significantly more rapid method of assessment. The clinical usefulness of the model was reinforced by its ability to distinguish between appropriately grown preterm low-birth weight (LBW) and growth retarded term LBW infants. The model is a rapid, reliable and useful method of determination of maturity at birth.

Anthropometry↗
PubMed1997

Timing of in vivo maturation of equine preovulatory oocytes and competence for in vitro maturation of immature oocytes collected simultaneously.

The objects of this study were to monitor the development of the cumulus complex and nuclear maturation in oocytes recovered from preovulatory follicles following treatment to induce ovulation and to investigate the in vitro maturation competence of oocytes recovered from smaller nonpreovulatory follicles of varying size. All follicles > or =5 mm in pony mares were individually punctured at 0, 6, 12, 24 and 35 h after an injection of LH to induce ovulation. The recovery rates of oocytes were 64% from 55 preovulatory follicles, 22% from 32 subordinate follicles and 52% from 227 small follicles. Cumulus expansion of the preovulatory oocytes occurred at 12 h post LH treatment while the metaphase I and II components of nuclear maturation were not completed until 24 and 35 h post LH respectively. For nonpreovulatory follicles, the frequency of atresia and oocyte competence for in vitro nuclear maturation both increased with increasing follicular size.

Animals↗
PubMed2001

Cell coupling and maturation-promoting factor activity in in vitro-matured prepubertal and adult sheep oocytes.

We examined some differences between prepubertal and adult ovine oocytes; in particular we analyzed the functional status of the cumulus-oocyte complex, protein synthesis during in vitro maturation, and because no information is available on prepubertal and adult sheep, maturation-promoting factor (MPF) fluctuations throughout meiotic progression both in prepubertal and adult sheep oocytes. After 24 h of maturation, percentages of MII oocytes were similar between prepubertal and adult animals. Electron microscopy examinations showed that prepubertal oocytes had fewer transzonal projections than adult oocytes. Methionine uptake was significantly lower in prepubertal cumulus-enclosed oocytes examined through meiotic progression. On the contrary, denuded prepubertal oocytes showed a higher methionine incorporation in the first 4 h of incubation compared with adult oocytes. We also found some differences in MPF activity between prepubertal and adult oocytes at MII stage. In fact, prepubertal MII oocytes had a significantly lower level of MPF activity than adult oocytes did and, after fusion with germinal vesicle oocytes, they were unable to induce nuclear breakdown and chromosome condensation 1-2 h post-fusion, whereas adult MII oocytes could induce these processes. Our findings show that the lesser competence of prepubertal oocytes could be due to morphological anomalies and alterations in physiological activity and that oocytes do not reach full developmental competence until puberty.

Animals↗
PubMed1986

Changes in the activity of the maturation-promoting factor during meiotic maturation and following activation of amphibian and starfish oocytes: their correlations with protein phosphorylation.

Changes in the extent of protein phosphorylation and their possible correlation with changes in the activity of maturation-promoting (MPF) factor were investigated throughout meiotic maturation and following activation of amphibian and starfish oocytes. Despite several exceptions in the pattern of phosphorylation of individual proteins, high and low levels of protein phosphorylation were found to be correlated with high and low levels of MPF activity. Both the extent of protein phosphorylation and MPF activity were found to drop upon parthenogenetic activation and to cycle synchronously thereafter in the amphibian. In contrast no drop in MPF activity or in the extent of protein phosphorylation was observed following activation of starfish oocytes with ionophore A23187. This suggests that changes of protein phosphorylation and of MPF activity are rather related to the progression of the cell cycle than directly to Ca2+-dependent activation reaction. In amphibians global protein kinase activity in homogenates was found to drop with MPF activity following activation. Changes in the ratio of threonine vs serine phosphorylation were also investigated during the course of meiotic maturation and activation in both amphibian and starfish oocytes: changes in the activity of MPF were found to be better correlated with changes in threonine than serine phosphorylation.

Adenosine Triphosphate↗
PubMed2000

Effects of wortmannin on the kinetics of GVBD and the activities of the maturation-promoting factor and mitogen-activated protein kinase during bovine oocyte maturation in vitro.

The present study was conducted with the objective of examining the effect of wortmanin, a specific PI 3-kinase inhibitor, on the kinetic of GVBD, and on the activities of the maturation-promoting factor (MPF) and mitogen-activated protein (MAP) kinase during bovine oocyte maturation. The time sequence for GVBD was not different between oocytes cultured with or without wortmannin. Most of the cultured oocytes were at the filamentous bivalents stage after 4 h of culture. Six hours after the start of culture, most of the oocytes possessed germinal vesicles with condensed bivalent, and by 10 h of culture nearly all of the cultured oocytes underwent GVBD. A gradual increase in MPF activity until 12 h of culture was observed in the presence and absence of wortmannin. A sharp decrease in MPF activity in oocytes cultured without wortmannin treatment was recorded at 14 h of culture. Thereafter, MPF regained activity, reaching a maximum level at 20 to 24 h of culture. For oocytes cultured with wortmannin, no decline in the activity of MPF was observed during the interval from 12 to 24 h of culture. For these oocytes the MPF activity remained nearly stable during this transition until the end of incubation. The presence of wortmannin in the maturation medium did not alter MAP kinase activity. Taken together, these observations indicate that inhibition of PI 3-kinase does not modulate the time sequence of GVBD or the pattern of MAP kinase activity in bovine oocytes. However, PI 3-kinase might be one of the molecules that regulate the sharp reduction in the activity of MPF during the MI/MII transition.

Androstadienes↗
PubMed1989

Mitosis-specific monoclonal antibody MPM-2 inhibits Xenopus oocyte maturation and depletes maturation-promoting activity.

MPM-2, a monoclonal antibody specific for cells in mitosis, recognizes a family of proteins that share a common phosphorylated epitope. In this study we have shown that during the maturation of Xenopus laevis oocytes induced by progesterone, phosphorylation of MPM-2 antigens coincided with the appearance of MPF activity. When MPM-2 (0.7-1.4 micrograms per oocyte) was injected into oocytes prior to progesterone stimulation, MPF activity failed to appear and induction of maturation was inhibited as judged by both germinal-vesicle breakdown and white-spot formation. Further, MPM-2 was able to neutralize as well as immunodeplete MPF activity from mitotic HeLa cell and mature oocyte extracts. These results suggest that MPM-2 recognizes either MPF itself or a protein(s) that regulates MPF activity and that the kinase that phosphorylates MPM-2 antigens may be a key component in the regulation of M-phase induction.

Animals↗
PubMed1985

Active maturation-promoting factor is present in mature mouse oocytes.

Cytoplasmic extracts of meiotically mature mouse oocytes were injected into immature Xenopus laevis oocytes, which underwent germinal vesicle breakdown within 2 h. Germinal vesicle breakdown was not inhibited by incubation of the Xenopus oocytes in cycloheximide (20 micrograms/ml). Identically prepared extracts of meiotically immature mouse oocytes, arrested at the germinal vesicle stage by dibutyryl cyclic AMP (100 micrograms/ml), did not induce germinal vesicle breakdown in Xenopus oocytes. The results show that maturation-promoting factor activity appears during the course of oocyte maturation in the mouse.

Animals↗
PubMed1998

Maturation-promoting factor (MPF) and mitogen activated protein kinase (MAPK) expression in relation to oocyte competence for in-vitro maturation in the mare.

In the equine species, a large proportion of oocytes fail to complete meiosis during in-vitro culture. The biochemical and molecular basis of this failure is unknown. The meiotic cell cycle is controlled in part by the maturation-promoting factor (MPF) and the mitogen-activated protein kinase (MAPK). In this study, we evaluated the oocyte competence for in-vitro maturation and the expression of MPF components (p34cdc2 and cyclin B) and MAPK after in-vitro culture. The maturation rate was influenced by the culture medium and the physiological stage of the mare at the time of oocyte recovery. We showed that MAPK and the two subunits of MPF were present in equine oocytes whatever the nuclear stage they reached after in-vitro culture and whatever the culture medium used. In incompetent oocytes, MAPK remained in its non-phosphorylated form, supposed to be inactive. In conclusion, the incompetence of equine oocytes to resume and complete meiosis is not due to the absence of p34cdc2, cyclin B or MAPK. Our results suggest that it is more probably due to a deficiency of regulators of MPF and/or to an inability to phosphorylate MAPK.

Animals↗
PubMed2004

Temperature induces gonadal maturation and affects electrophysiological sexual maturity indicators in Brachyhypopomus pinnicaudatus from a temperate climate.

In contrast to most of the previous studies in gymnotiform reproduction, which have been conducted in the tropical region, this study examines a gymnotid from the temperate region in both the natural habitat and the laboratory. The gonadal histology of Brachyhypopomus pinnicaudatus is described for the first time. The male had a paired, lobular testis of the unrestricted spermatogonial type, and females a paired saccular cystovary. Analysis of gonads and their annual cycle enabled us to confirm the breeding season and to conclude that this species is a multiple spawner. Water temperature and photoperiod showed the expected annual cycles for the region. High temperature and a 14 h:10 h L:D photoperiod in the natural habitat coincided with (1) mature gonadal stages, (2) electrophysiological sexual dimorphism: males present a lengthened negative phase in their electric organ discharge (EOD) and (3) decreased temperature sensitivity of the EOD: the waveform does not change when temperature increases above 20 degrees C. Acclimation to sustained high temperature (30 days, 28 degrees C, 12 h:12 h L:D, low conductivity) induced gonad maturation along with EOD dimorphism. Our data show that high environmental temperature is enough to trigger sexual maturity in Brachyhypopomus pinnicaudatus from a temperate climate.

Acclimatization↗
PubMed1993

Maturation-promoting factor (MPF) is responsible for the transformation of sperm nuclei to metaphase chromosomes in maturing bovine oocytes in vitro.

Bovine oocytes at the germinal vesicle stage were inseminated in Brackett and Oliphant's medium in the presence of BSA (10 mg ml-1), caffeine (5 mmol l-1) and heparin (10 micrograms ml-1). When oocytes were transferred into tissue culture medium (TCM)-199 containing 10% fetal calf serum (FCS) with or without 6-dimethylaminopurine (6-DMAP; 2 mmol l-1) 8 h after insemination and cultured for 15-40 h at 39 degrees C in 5% CO2 in air, 74-83% of oocytes were penetrated and polyspermy (67-80%) was common. At 40 h after culture in 6-DMAP-free medium, 65% and 63% of unpenetrated and penetrated oocytes, respectively, reached metaphase II or beyond. A few (6%) oocytes were activated and contained both male and female pronuclei. Sperm metaphase chromosomes were observed in 90% of the penetrated oocytes. Penetration by more than four spermatozoa greatly retarded the meiotic maturation of the oocyte. However, sperm chromosomes were never observed in oocytes cultured in 6-DMAP supplemented medium and oocyte maturation did not proceed beyond the stage of prometaphase I. These results demonstrate the possible participation of maturation-promoting factor in metaphase chromosome formation in spermatozoa.

Adenine↗
PubMed1995

Correlation of sexual maturation with stature and body weight & dental maturation in southern Chinese girls.

Correlation of stature and body weight and the eruption of permanent teeth with four sexual maturity criteria (menarche, pubic hair, axillary hair and breast development) was studied in 102 Southern Chinese girls aged between 11 years, 9 months and 12 years, 3 months and born and brought up in Hong Kong. With respect to all four selected criteria, the early sexual maturers were significantly taller and heavier and had more erupted permanent teeth with p values ranging from < 0.01 to < 0.001 levels than the late maturers.

Adolescent↗
PubMed1997

[Premature labor, determination of fetal lung maturity and medicamentous induction of lung maturation].

Preterm delivery continues to be one of the main causes of perinatal mortality and morbidity, comprising about 8% of all deliveries. The percentage of the most jeopardized preterm newborns weighing less than 1500 g is about 1, however, can be several fold higher in perinatal centers. Respiratory distress syndrome, intracranial hemorrhage, persistent fetal circulation as well as enterocolitis represent prominent complications. Avoiding preterm delivery in cases of preterm labor is attempted by application of magnesium sulfate, beta sympathomimetics or non-steroidal antiphlogistics. Is preterm delivery desirable, however not absolutely indicated, knowing the status of the fetal lung maturity may be helpful in the decision making process. This can nowadays best be achieved by determining the surfactant albumin-ratio by possibly repeatedly withdrawing amniotic fluid by amniocentesis. When inducing lung maturation, application of corticosteroids crossing the placenta is favoured. With impending preterm delivery this should always be given a try, independent from the time expected to be left until delivery- and also below the completed 27th week of pregnancy. Prenatal induction of lung maturation and postnatal application of surfactant are to be looked at as complementing therapeutic concepts in the immature neonate.

Adrenal Cortex Hormones↗
PubMed1996

In vitro maturation of bovine oocytes in the presence of growth hormone accelerates nuclear maturation and promotes subsequent embryonic development.

Regulatory effect of GH on follicular growth and development in the cow is well documented. The aim of this study was to investigate the role of GH on in vitro bovine oocyte maturation. Therefore bovine cumulus oocyte complexes (COCs) were cultured in M199 without FCS and gonadotropins and in the presence of 10, 100, or 1,000 ng/ml bovine GH (NIH-GH-B18). The COCs were incubated at 39 degrees C in a humidified atmosphere with 5% CO2 in air and nuclear stage was assessed after 2, 4, 8, 16, 22, and 24 hr of incubation using DAPI staining. To assess the effect of GH on developmental capacity of the oocytes, COCs were incubated in the presence of GH for 22 hr, followed by IVF and in vitro embryo culture. Cultures without GH served as controls. For subsequent development, the embryos were cultured in M199 supplemented with 10% FCS on a monolayer of BRL cells. Embryos were scored morphologically and the efficiency of the culture system was evaluated as (1) the percentage of cleaved embryos 4 days after IVF, (2) the percentage of blastocysts on day 9 expressed on the basis of the number of oocytes at the onset of culture, and (3) the percentage of hatched blastocysts on day 11 expressed on the basis of the total number of blastocysts present at day 9. GH (100 and 1,000 ng/ml) significantly accelerated nuclear maturation (P < 0.001). At 4 and 8 h the percentage of oocytes in GV stage after GH treatment (54% and 19%) was significantly lower than the control (64% and 41%). Similarly at 16 and 22 h the percentage of oocytes in MII stage was significantly higher in the GH-treated group; (58% and 77%) and (46% and 62%) for GH and control respectively. The number of oocytes in MII beyond 22 hr of culture did not differ; 100 and 1,000 ng/ml GH induced significant cumulus expansion (P < 0.05), which was not observed in the absence of GH. Addition of 100 and 1,000 ng/ml GH during maturation significantly (P < 0.01) enhanced subsequent cleavage rate from (64% and 67%) in control to (75% and 81%) in GH-treated group; embryonic development in terms of day 9 blastocyst formation was also significantly increased in the presence of GH (29% and 34%) compared to the control (18% and 24%). The hatchability of the blastocysts was not influenced by GH. From the present data, it can be concluded that GH present during IVM has a beneficial effect on subsequent development.

Animals↗
PubMed1997

Effects of epidermal growth factor and follicle-stimulating hormone during in vitro maturation on cytoplasmic maturation of porcine oocytes.

The present study was undertaken to investigate the influence of epidermal growth factor (EGF) and follicle-stimulating hormone (FSH) during in vitro maturation on cytoplasmic maturation of porcine oocytes as revealed by the success of fertilization and by the changes in the pattern of protein synthesis in oocytes and cumulus cells. For fertilization studies, oocyte-cumulus cell complexes (OCC) were cultured in media containing human recombinant EGF (1 ng/ml) or FSH (1.5 microg/ml) or both for 44 hr prior to fertilization with fresh sperm for 6-8 hr. The oocytes were then fixed, stained, and examined as whole mounts following an additional 14 hr of culture. Addition of EGF, FSH, and EGF + FSH significantly increased the proportion of oocytes reaching MII stage. The addition of EGF alone significantly decreased the percentage of polyspermic oocytes and increased the proportion of monospermic oocytes forming 2 normal pronuclei. FSH abolished these effects of EGF and significantly increased the percentage of polyspermic oocytes forming more than 2 pronuclei when added alone or with EGF. For protein analysis, OCC were cultured in media containing the above hormones for 6, 24, and 44 hr and exposed to 0.5 mCi/ml L-[35S]methionine during the last 3 hr of cultures. The oocytes and cumulus cells were separated prior to lysis in SDS sample buffer, and denatured polypeptides were separated by 1-dimensional SDS-PAGE. In the oocyte, addition of EGF and FSH alone stimulated the synthesis of 34, 45, and 97 kDa proteins after 6 hr of culture; however, the addition of EGF and FSH together was without any effect. After 24 hr, EGF alone inhibited the synthesis of these peptides, whereas FSH alone and with EGF maintained the stimulation of synthesis of 34 and 45 kDa proteins. Two additional peptides corresponding to 66 and 200 kDa appeared at this time as a result of exposure to FSH alone or with EGF. After 44 hr of culture, these 2 new peptides were observed in all groups and the stimulatory effect of FSH and FSH + EGF was still evident. An additional peptide of 26 kDa appeared at this time as a result of FSH and EGF + FSH treatments. In the cumulus cells, EGF and FSH each alone induced the synthesis of a new peptide of 26 kDa after 6 hr of culture. FSH when added alone or with EGF induced the synthesis of an additional peptide of 29 kDa, the synthesis of which remained unchanged at 24 and 44 hr. After 24 hr, FSH alone and in combination with EGF induced the synthesis of an additional 38 kDa peptide and its synthesis was still maintained at 44 hr. EGF alone had no effect on protein synthesis in cumulus cells at 24 and 44 hr. These studies indicate that EGF may have a physiological role in the regulation of cytoplasmic maturation of porcine oocytes.

Animals↗
PubMed1993

Developmental ability of enucleated bovine oocytes matured in vitro after fusion with single blastomeres of eight-cell embryos matured and fertilized in vitro.

Single blastomeres from eight-cell stage bovine embryos matured and fertilized in vitro were electrically fused with enucleated oocytes matured in vitro. In experiment 1, The percentage of these reconstituted embryos developed to the two- to eight-cell stage 48 hr after electrofusion was increased when both the eight-cell embryos and the enucleated oocytes were derived from oocytes cultured with granulosa cells (14% vs. 38%). In experiment 2, the relationship between activation of oocytes and developmental ability of reconstituted embryos was examined. Although both ethanol and electrical stimulation efficiently induced parthenogenetic activation of oocytes matured in vitro for 26-28 hr (ethanol, 89%; electrical stimulation, 73%), the ratio of the second polar body extrusion differed (80% vs. 22%). Ethanol-treated enucleated oocytes, however, were not significantly different from the early cleavage of the reconstituted embryos 48 hr after electrofusion (nontreated, 38%; treated, 43%). In experiment 3, reconstituted embryos at the two- to eight-cell stage 48 hr after the electrofusion were cocultured with granulosa cells for 6-7 days. Of 69 embryos, one developed to a morula and three developed to blastocysts.

Animals↗
PubMed1998

Secretion of recombinant pro- and mature fungal alpha-sarcin ribotoxin by the methylotrophic yeast Pichia pastoris: the Lys-Arg motif is required for maturation.

alpha-Sarcin is a ribosome-inactivating protein from the mold Aspergillus giganteus. The methylotrophic yeast Pichia pastoris has been transformed with two plasmids (pHILD2prealphaS and pHILS1prealphaS), which contain the complete alpha-sarcin cDNA, including its original fungal leader peptide, under the control of yeast alcohol oxidase promoter. The second one is indeed fused to the signal sequence of P. pastoris acid phosphatase. The transformed yeasts secreted both mature and pro-alpha-sarcin. The presence of this pro-alpha-sarcin in the yeast extracellular medium is due to an inefficient recognition of the pro-sequence by a putative Kex2p-like endopeptidase. A third plasmid accounting for a single mutation of the alpha-sarcin leader peptide was designed to produce a more efficient Kex2p recognition motif. This approach resulted in the extracellular production of only the mature protein, suggesting the existence of a two-step mechanism for processing its leader peptide. This recombinant alpha-sarcin is identical to the original fungal protein, according to activity and spectroscopic criteria. In addition, pro-alpha-sarcin, which has been characterized for the first time, also exhibits ribonucleolytic activity as the mature protein does. Therefore, protection of the producing cells against this kind of ribotoxins may depend on an efficient recognition of the signal sequence followed by translocation of the nascent polypeptide to the endoplasmic reticulum.

Amino Acid Sequence↗