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M Illera

Publications and source records attributed to M Illera.

At least 37 records · Page 2Linked to original sources
PubMed1995

Influence of growth factors on the time-dependent meiotic progression of the bovine oocytes during their in vitro maturation.

The present study examines the effects of epidermal growth factor (EGF), insulin-like growth factor-I (IGF-I), and the presence of cumulus cells on the meiotic progression of the bovine oocyte maturation. Oocytes were aspirated from 2-8 mm ovarian follicles, and the cumulus-oocyte complexes (COC) obtained (n = 2,729) were divided into COC or denuded oocytes. They were then cultured in four defined treatments comprising TCM-199 and growth-factors: control (no growth factor), IGF-I, EGF, and EGF+IGF-I. Each treatment group of oocytes was cultured during 6, 12, 18, 24, and 30 h; the oocytes were fixed and stained at the end of each 6 hour interval from 0 to 30-h, and were assessed for their nuclear maturation stage. Germinal vesicle (GV) and metaphase II (MII) stages present were used as the final parameters for data analysis. The results indicate that treatments with growth factors enhanced the incidence of GV activation and MII stage in all the culture periods. Maximal stimulation for nuclear maturation occurred with EGF+IGF-I. As regards the denuded oocytes, no positive effects on nuclear maturation rates were observed for any treatment. These results suggest that EGF and IGF-I, singly and combined, stimulate the meiotic progression significantly, and this effect can be induced by a positive signal which is transferred from cumulus cells to oocyte.

Animals↗
PubMed1994

Enhancement of cumulus expansion and nuclear maturation during bovine oocyte maturation in vitro by the addition of epidermal growth factor and insulin-like growth factor I.

This study was carried out to identify the possible effects of epidermal growth factor (EGF) and insulin-like growth factor-I (IGF-I) on cumulus expansion and nuclear maturation in bovine oocytes matured in vitro in serum-free media. Bovine follicular oocytes were matured in vitro and were then classified as cumulus cell-enclosed oocytes or denuded oocytes. They were then cultured for 24 h in TCM-199 (tissue culture medium-199) with EGF (50 ng ml-1), IGF-I (100 ng ml-1) and EGF plus IGF-I (50 and 100 ng ml-1, respectively). At the end of the culture period, the morphology of oocytes was evaluated for cumulus expansion and nuclear stage of maturation. In Expt 1, percentages of oocytes reaching maximum cumulus expansion were: 12.5% (control), 46.5% (EGF), 15.2% (IGF-I) and 52.8% (EGF plus IGF-I). In Expt 2, the respective rates of nuclear maturation were: 35.6%, 52.1%, 45.5% and 61.4% for cumulus cell-enclosed oocytes, and 35.3%, 46.6%, 45.4% and 42.5% for denuded oocytes; the same growth factor treatments were used in both cases. There was no significant effect of IGF-I on cumulus expansion. Maximum rates of cumulus expansion and nuclear maturation were obtained in the presence of both growth factors. These results lead to the following conclusions: (i) EGF, either alone or together with IGF-I, stimulates cumulus expansion; and (ii) both growth factors, acting alone or together, enhance nuclear maturation in oocytes surrounded by compact cumulus cells.

Animals↗
PubMed1993

Determination of follicular fluid estradiol levels by enzyme-linked immunosorbent assay.

A direct competitive heterologous enzyme-linked immunosorbent assay (ELISA) was developed and validated to determine follicular fluid estradiol levels of different antral follicular sizes (small, medium, and large) obtained from the ovaries of heifers in the follicular phase of the estrous cycle. Polyclonal antiestradiol antibodies were raised in New Zealand White rabbits using 6-keto-1,3,5(10)-estratriene-3,17 beta-diol 6-carboxymethyloxime: bovine serum albumin as immunogen and characterized by the usual methods. Horseradish peroxidase conjugated to 1,3,5(10)-estratriene-3,17 beta-diol 3-hemisuccinate was used as a label. The concentration range used for the standard curve was 0 to 1 ng per well. The low detection limit of the technique was 0.3 pg per well with a sensitivity at 50% binding of 93.62 pg per well. Intraassay and interassay CV (%) were < 5.3% and < 7.0%, respectively (n = 10). The recovery rate of the known estradiol concentrations added to follicular fluid averaged 96.1 +/- 1.3%. Compared with a radioimmunoassay (RIA), the values of ELISA were highly correlated (r = 0.99, P < 0.005). This assay was used to quantify follicular fluid estradiol concentrations without previous extraction in three antral follicular sizes; small (< 5 mm), medium (5.1 to 10 mm), and large (10.1 to 20 mm). The mean +/- SE follicular fluid estradiol concentrations were 77 +/- 5.2 ng/ml (n = 490) in small follicles, 111 +/- 19 ng/ml (n = 65) in medium follicles, and 496 +/- 144 ng/ml (n = 45) in large follicles.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Development and validation of competitive ELISA to determine follicular fluid progesterone concentrations.

A simple, direct and reliable heterologous ELISA was developed and validated to determine follicular fluid progesterone concentrations in 10- to 20-mm antral follicles in heifers. A competitive ELISA was developed, using a policlonal antisera raised in New Zealand white rabbits and horseradish peroxidase as label. Standard curve covered a range between 0 and 1 ng per well. The intra- and inter-assay coefficients of variation (CV) were 6.54 and 8.27%, respectively (n = 10). The low detection limit was 1 pg per well with a sensitivity of 50% binding 83.17 pg per well. Comparison of ELISA with RIA showed a correlation coefficient of 0.98. A total of 34 follicles obtained from heifers in the follicular phase of the estrous cycle were tested, and the mean progesterone concentration was 86.72 +/- 20.39 ng/ml. These results were similar to those previously reported for the same species, age, follicular size and stage of cycle.

Journal Article↗
PubMed1993

[Specific actions of growth factors (EGF and IGF-I) on the in vitro maturation of bovine oocytes].

Growth factors (EGF and IGF-I) have different actions on mammalian cells such as proliferation and differentiation. The effect of EGF and IGF-I was examined on in vitro matured bovine oocytes. Immature oocytes were obtained by follicular aspiration from slaughtered heifer ovaries and classified in two groups, with or without cumulus cells. Oocytes (n = 1,037) were cultured in a serum-free media (TCM-199) for 24 hours at 39 degrees C in absence of hormones and were divided in 5 treatments: control, EGF (20 ng/ml and 50 ng/ml), IGF-I (100 ng/ml) and EGF + IGF-I (50 ng/ml + 100 ng/ml). Results suggest that the EGF + IGF-I treatment increases significantly (p < 0.01) the maturation rate (60.3%) as compared to control medium (36.5%) in cumulus cell-enclosed oocytes. No significant differences were observed between the treatments in the denuded oocytes. The effect of EGF + IGF-I added to the maturation media seems to be mediated by the surrounding cumulus cells and enhanced the in vitro maturation rate on cumulus cell-enclosed bovine oocytes.

Animals↗
PubMed1992

[Photoperiod variations of various blood biochemistry constants in the rabbit].

Biochemical blood parameters generally show fluctuations during the day. The aim of this study is to determine the variations of the following parameters: hemoglobin, glucose, triglycerides, ASAT, ALAT, urea and creatinine in New Zealand white (NZW) rabbits, kept under five different circadian rhythms (12/12, 14/10, 10/14, 16/8, 8/16, light/dark). These parameters were analyzed by using a reflection photometer (Reflotron). Most results are found within the physiological range for this species but there are significant differences among cycles. These findings could be explained by the dependence of the biochemical blood parameters on the light/dark cycle. It can be concluded that the most useful cycle to find fewer variations of the biochemical blood parameters in NZW rabbit is 12/12 light/dark cycle.

Alanine Transaminase↗
PubMed1990

[Photoperiodic variations in plasma concentration of testosterone in the rabbit].

The photoperiodic variations of testosterone plasmatic levels in male rabbits have been studied. The animals were subjected to the influence of three circadian rhythms: 12/12, 14/10 and 10/14 h of light/darkness. The hormone assay was carried out using an enzymeimmunoassay method (Competitive ELISA). Blood samples were of two different types: seriated and non-seriated, to find if these might be any differences in the results. It is concluded that testosterone plasmatic levels are within physiologic values (0.3-10.0 ng/ml), although differences depending on the light/darkness cycle and on the type of blood extraction are remarkable; for this reason the selection of the circadian rhythm will depend on the experimentation that is to be carried out.

Animals↗
PubMed1987

Developmental changes induced by glucocorticoids treatment in breeder quail (Coturnix coturnix japonica).

The effects produced in offspring by corticosterone treatment to breeder quail were investigated. The breeders received corticosterone orally every day during 7 days. The total dose administered was 3.15 mg/quail/7 days. The quail from treated breeders have a decreased rate of body growth during the experimental period. The studied metabolic and nutritives parameters were smaller than the control group, however, the relative indices were similar. The breeders treated with corticosterone produce quail smaller than controls, but the pattern during the growth period is similar, there it can be observed by the same relative indices.

Animals↗
PubMed1987

Unipolar thoracic electrocardiograms in which P waves of relative uniformity occur in male horses.

Bipolar and unipolar limb leads and unipolar thoracic lead ECG were obtained from 100 male crossbred horses. P-wave morphologic features were classified according to positivity negativity and monopolarity dipolarity, and the percentage of horses that had P waves of a given morphologic class in each lead was calculated. P-Wave morphologic features of 4 precordial leads were most uniform, with greater than 80% of the horses having a single configuration.

Animals↗
PubMed1987

Unipolar thoracic electrocardiography that induces QRS complexes of relative uniformity from male horses.

Electrocardiograms were obtained from 100 male crossbred horses. In addition to standard limb leads, leads were taken from 12 points on the thorax. The QRS complexes were categorized into 1 of 8 forms on the basis of configuration and amplitudes of component deflections. Relative uniformity of QRS was determined for each lead, using the percentage of horses that possess a particular configuration. All unipolar thoracic leads, except those coplanar with the frontal plane, and lead aVR had great uniformity, with greater than 80% of the horses with a QRS of similar contour.

Animals↗
PubMed1986

[Changes in thyroid function caused by continuous treatment with thiouracil in rats].

Serum concentration evolution of thyroxine and triiodothyronine, and thyrotropin (TSH), have been studied in rats while they were given 6-propylthiouracil (PTU) as antithyroid drug, and during the recovery period after suppression of treatment. In the same way thyroid hypertrophy and plasmatic levels of thyrotropin were correlated. Animals received orally a daily dose of 1 mg/100 g body weight during thirty-five days and had a two week recovery period. Thyroid hormone concentrations in plasma were determined by immunoenzymatic assay ELISA with peroxidase as labelled enzyme. From the results obtained, it can be stated that chronic administration of PTU implies a continuous decrease in thyroid hormone concentrations in plasma, reaching nearly zero values, while after treatment, levels recover their normal values in a week's time. A parallelism exists between thyroid hypertrophy and pituitary TSH hypersecretion, due to a decrease in thyroid hormone levels.

Animals↗
PubMed1982

[Comparative study of the effect of glucocorticoids on nitrogen metabolism in adult male and non-laying female quail (Coturnix coturnix japonica)].

The effects of glucocorticoids on nitrogen metabolism have been studied in three different groups of quail: a) control animals; b) quail treated with cortisol; c) quail treated with corticosterone. All the experiments were carried out in adult male and non-laying female animals. During the 7 day period that the experiments lasted, hormones were administered daily by via oral at 4 mg/100 g body weight/7 day doses. While body weight, food intake, nitrogen balance and liver weight, in the treated animals stayed under the values of the control group, in both males and females, their uric acid excretion and hepatic glycogen were always higher. Values, in general, were similar for both males and females.

Animals↗