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Biomedical subjects

F Miro

Publications and source records attributed to F Miro.

10 recordsLinked to original sources
PubMed2005

Dynamics of urinary levels of hCG during early pregnancy and accuracy of the home pregnancy test.

The paper ‘Dynamics of urinary levels of hCG during early pregnancy and accuracy of the home pregnancy test’ has been retracted at the request of the authors. Since initiating the work 3 years ago improvements have been made to home pregnancy tests, and the device used in the study is no longer commercially available. The authors are conducting a similar study with a new pregnancy test device which suggests that some of the conclusions drawn in the retracted paper could now be misleading to health professionals and consumers.

Retraction of Publication as Topic↗
PubMed2004

The onset of the initial rise in follicle-stimulating hormone during the human menstrual cycle.

BACKGROUND: The rise in FSH (FSHr) that leads to the recruitment of a cohort of follicles during the menstrual cycle occurs during the luteal-follicular transition, however, it is unclear whether it consistently occurs on one particular day, or is subjected to reproductive ageing. METHODS: We determined the FSHr in 836 complete menstrual cycles from 102 women with regular menses using an algorithm, and additionally compared the relative variation in FSH during the last 14 days of the cycle. Possible effects of reproductive ageing on the onset of FSHr were also investigated. RESULTS: The day of FSHr follows a normal distribution with a median value of -4 (relative to first day of menses), mean -4.1 and SD 2.1. Analysis of the relative changes in FSH during the last 14 days of the cycle revealed the first significant rise on day -4 (P=0.0033), coinciding with the first significant drop in estrogens (P=0.0002). No effect of chronological age, or initial FSH levels, on FSHr was found, however, there was an inverse relationship between total follicular phase length (from day of FSHr to LH peak) and initial FSH levels (P<0.0001). CONCLUSIONS: The initial FSH rise in the cycle occurs consistently 4 days before menses, is related to a drop in estrogen levels, and is not affected by reproductive ageing.

Adult↗
PubMed2004

Origins and consequences of the elongation of the human menstrual cycle during the menopausal transition: the FREEDOM Study.

The menopausal transition is characterized by the appearance of elongated cycles, which become longer and more frequent as menopause approaches. Several endocrine abnormalities have been attributed to these cycles; however, no quantitative studies of their causes and consequences exist to date. This study is based on sequential daily urinary concentrations of FSH, LH, estrone 3-glucuronide (E1G), and pregnanediol 3-glucuronide (PdG) from 34 women with perimenopausal menstrual irregularity (total of 289 cycles). The timing of ovarian response was determined as the day of E1G take-off (ETO). Other parameters measured were the mean FSH concentration before ETO (FSH(ETO)) and the midluteal levels of PdG, E1G, and LH. There was a strong parallelism between ETO and cycle length variability. FSH(ETO) levels increased gradually with ETO. Both ETO and FSH(ETO) were inversely related to luteal PdG and directly related to E1G. PdG and LH levels were inversely related. All comparisons were highly significant (P < 0.0001). We conclude that delayed ovarian response underlies the elongation of the menstrual cycle in the menopausal transition, which is likely to be caused by a temporary lack of ovarian responsiveness to FSH. A progressive decline in luteal PdG with increased E1G occurs in association with these trends.

Adult↗
PubMed2004

Relationship between follicle-stimulating hormone levels at the beginning of the human menstrual cycle, length of the follicular phase and excreted estrogens: the FREEDOM study.

Although reproductive aging has been separately related to elevated FSH and shorter follicular phase (FP), the direct association between both parameters has not been investigated. Also, the exact effects of increased FSH on estrogen production are yet to be established.A large database of daily urinary concentrations of FSH, LH, and estrone 3-glucuronide (E1G) from 37 regularly menstruating women (median 11 cycles per patient) was used. Initial FSH levels (iFSH) were estimated as the mean value of d 1-5. The day of E1G take-off (ETO) was determined by an algorithm, and accordingly, the FP was divided into early (d 1 to ETO) and late (ETO+1 to LH peak). FP maximum and integrated E1G were calculated. Subjects were distributed according to their mean iFSH into three categories (</=5, >5 to 10, and >10 IU/liter). There was a gradual decrease in FP length with increasing category (15.2 +/- 3.8, 14.1 +/- 3.6, and 13 +/- 2.6 d, respectively; P < 0.0001). A similar effect occurred in early FP (7.5 +/- 4, 6.4 +/- 3.7, and 5.4 +/- 2.7; P < 0.0001); in contrast, late FP was unaffected (7.7 +/- 2.1, 7.7 +/- 2.1, and 7.6 +/- 2.4; P = 0.86). No consistent increase in E1G was found with advancing iFSH category; however, women with mean initial LH higher than 6 IU/liter had significantly elevated maximum (P < 0.0001) and integrated (P = 0.002) E1G.FP length decreases in parallel with increasing iFSH, with a selective effect on the early FP. Increased FSH does not affect E1G; however, elevated initial LH level was related to higher E1G.

Adult↗
PubMed2001

Changes due to age in the kinematics of trotting Andalusian foals.

The purpose of this study was to evaluate the effect of growth on biokinematic characteristics at the trot in a group of 9 Andalusian foals from age 12 to 36 months in order to identify which stride variables change or remain invariable. Biokinematic analysis was performed by using a computer-assisted videography system (25 Hz frame rate). An increase in stride length as well as the fore- and hindlimb stride duration was found. A tendency to increase flexion of the shoulder, elbow and carpal joints was observed while the forelimb fetlock increased its maximal extension. In the hindlimb, most of the differences were exhibited by the hip and stifle joints, which showed a tendency to a lesser flexion with age. However, at landing the extension was bigger. The hindlimb fetlock extended more in older foals, whereas flexion decreased. Significant differences in the maximal extension and flexion instants in the forelimb joints were not detected (except in the elbow joint). The same was found in the angular range of motion (ARM) of the scapula inclination and the shoulder and forelimb fetlock joints. Differences in retraction-protraction angles in both the fore- and hindlimbs were very slight, and ARM values for these parameters were similar in all age groups. It can be concluded that Andalusian horses modified their locomotor pattern at the trot between age 12 and 36 months, particularly up to 24 months, by increasing stride length as well as shoulder, elbow and carpus flexion, while hip and stifle flexion decreased and hindlimb joints were more extended during the stance phase. One of the most striking features was that maximal retraction and protraction angles did not change in foals age 12-36 months in either fore- or hindlimbs. These results could be useful for the prediction of some kinematic parameters of mature horses from data obtained at younger ages.

Age Factors↗
PubMed1996

Effects of growth hormone releasing hormone on rat ovarian steroidogenesis.

During the last decade, it has been shown that each part of the somatotrophic axis can influence granulosa cell function. Growth hormone releasing hormone (GHRH) may be effective through the release of hypophyseal growth hormone (GH) and the subsequent increase of insulin-like growth factors (IGF). There is also some evidence that GHRH could act directly on ovarian function. The aim of this study was to determine the mechanism through which GHRH affects granulosa cell steroidogenesis in the ovary. Granulosa cells were obtained from immature, oestrogen- treated rats supplemented with or without follicle stimulating hormone (FSH) in vivo and were cultured for 48 h to evaluate steroid production. GHRH was administered either in vivo at the same time as FSH, or in vitro in the presence or absence of testosterone and FSH. Our results show that co-treatment with GHRH and FSH in vivo induced significant increases in plasma IGF-I concentrations and steroid production by cultured granulosa cells. The addition of GHRH to culture medium did not significantly alter steroid production by either non-differentiated (no FSH in vivo) or differentiated (FSH in vivo granulosa cells. In contrast, treatment in vitro with IGF-I significantly increased steroidogenesis in both cases. Our results suggest that any physiologically significant effect of GHRH on ovarian function is probably to be exerted via activation of the somatotrophic axis and the subsequent amplification of ovarian FSH responsiveness by IGF-I.

Animals↗
PubMed1996

GnRH-induced calcium mobilisation and inositol phosphate production in immature and mature rat ovarian granulosa cells.

In rat ovarian granulosa cells the effects of GnRH are determined by the state of granulosa cell development with mainly inhibitory actions in immature cells and stimulatory actions in differentiated mature cells. These developmentally related effects of GnRH may arise from changes in either one or more of the signal transduction pathways activated by GnRH. The present study therefore measured downstream signalling events associated with the activation of the phospholipase C (PLC) signal transduction pathway in both mature and immature rat ovarian granulosa cells. Results showed that GnRH produced similar total inositol phosphate and intracellular calcium ([Ca2+]i) responses in both immature and mature granulosa cells. In contrast to the biphasic GnRH-induced [Ca2+]i response in pituitary gonadotropes, stimulation of the endogenously expressed GnRH receptor in both immature and mature granulosa cells produced a prompt monophasic rise in [Ca2+]i. This calcium transient was abolished by pretreating either cell type with a potent GnRH receptor antagonist or the PLC inhibitor U73122, demonstrating a GnRH receptor-specific activation of PLC. Similarly, pretreatment of cells with the [Ca2+]i antagonists thapsigargin or cyclopiazonic acid abolished the GnRH-induced calcium transient, whereas EGTA and nifedipine, a voltage-operated calcium channel (VOCC) antagonist, had no effect. These results suggest that in either immature or mature granulosa cells GnRH mobilises calcium from thapsigargin/cyclopiazonic acid-sensitive [Ca2+]i stores but does not involve the influx of extracellular calcium through VOCCs. We conclude that GnRH-induced stimulation of the PLC signal transduction pathway is independent of the stage of granulosa cell maturity and that alternative mechanisms account for the opposite effects of GnRH on gonadotrophin-induced steroidogenesis in mature and immature rat granulosa cells in vitro.

Animals↗
PubMed1991

Development of ovarian cysts during gonadotrophin-releasing hormone agonists (GnRHa) administration.

The incidence of ovarian cyst formation during stimulation with additional pituitary suppression was retrospectively studied in 359 patients included in our in-vitro fertilization (IVF) programme. Women were classified according to the type of pituitary desensitization with subcutaneous buserelin used in group A (long protocol; n = 285) and group B (short protocol; n = 74). The rate of appearance of single follicular ovarian cysts for group A was 9.82% and for group B 22.97% (P less than 0.005). Ovarian cystic formations were usually asymptomatic and nonfunctional. The presence of these cysts did not seem to interfere with the ovarian response to stimulation treatment. Oocyte retrieval and pregnancy rate were similar between patients who developed ovarian cysts during gonadotrophin-releasing hormone analogue (GnRHa) therapy and those without cyst formation. These results suggest that ovarian cysts developing during GnRHa treatment are probably the consequence of the initial gonadotrophin rise and that the presence of ovarian cysts in these conditions should not be considered a necessary cause of cancellation for IVF patients.

Adult↗
PubMedDate not supplied

Effects of training on fibre composition in rat gastrocnemius muscle.

Forty-eight adult Wistar rats were divided into four groups for experimentation. The group I was used as a control and groups II, III and IV underwent progressive treadmill training. Samples of the red and mixed portions of m. gastrocnemius (lateral head) were stained with the histochemical technique of m-ATPase to determine the percentage of type I, IIA and IIB fibres, and with NADH-TR, in order to quantify variations in "low-oxidative" fibre percentages. The results showed that progressive training did not lead to statistical variations in the percentage of type I fibres. However, the proportion of type IIA fibres rose, while that of IIB fibres fell, in both cases significantly. Variations were more marked in mixed than in red Gastrocnemius muscle. A clear decrease was noted in "low-oxidative" fibres, which were virtually absent from red portion. This decrease was more marked, and occurred more rapidly, than in type IIB fibres.

Animals↗