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M Safi

Publications and source records attributed to M Safi.

7 recordsLinked to original sources
PubMed1999

Insulin-like growth factors in the regulation of avian ovarian functions.

In the past three decades, overwhelming evidence has accumulated to show that insulin-like growth factor (IGF)-I and -II, their receptors and binding proteins (IGFBP) (the IGF system), have major roles to play in the regulation of ovarian function in mammals. Although studies in birds did not start until 5-6 years ago, the limited information thus far available suggests that the IGFs act as autocrine/paracrine regulators of follicular growth and differentiation, just as observed in mammals. The genes for IGF-I and -II, type-I IGF receptor, IGFBP-2, and IGFBP-5 are expressed in both granulosa and theca cells of the chicken ovary. The mechanisms by which the IGF system controls ovarian function in the avian species are complex and involve interactions with the gonadotrophins (LH and FSH), growth hormone, and even other growth factors. Effects are different between strains and nutritional status.

Animals↗
PubMed1999

Effects of timing and duration of feed restriction during rearing on reproductive characteristics in broiler breeder females.

The objective of this study was to determine whether there exists a critical period during rearing when restricted feeding of broiler breeder hens can be most beneficial on subsequent egg production. Broiler breeder pullets were subjected to combinations of either ad libitum or restricted feeding during three periods before sexual maturity. Body weight gain, feed intake, and egg production were recorded. Ovary and oviduct weights were noted at age of first oviposition. At 15 and 18 wk of age and at age of first oviposition, chicken luteinizing hormone releasing hormone-I (cLHRH-I) in the median eminence and the levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the pituitary and plasma were determined. The results demonstrated that alternation between ad libitum and restricted feeding during rearing changed the growth curves of the birds. Feed restriction from 7 to 15 wk followed by either ad libitum or restricted feeding led to improved reproductive performance, suggesting that long-term feed restriction may not be necessary to attain good reproductive performance. The birds restricted from 7 to 15 wk of age had higher proportional weights of ovary (> or = 1.7%) and oviduct (> or = 1.58%) at age of sexual maturity. The cLHRH-I levels in the median eminence and gonadotrophin contents in the pituitary followed that of growth in response to feeding levels and timing of feeding and could be related to the timing of the onset of lay. At age of first egg, all groups had similar levels of cLHRH-I, LH, and FSH. However, no clear effect of level of feed intake or time period of restriction could be observed for plasma LH or FSH concentrations.

Animal Feed↗
PubMed1998

Quantification of inhibin/activin alpha and betaA subunit messenger ribonucleic acid by competitive reverse transcription-polymerase chain reaction in chicken granulosa cells during follicular development.

The very sensitive quantitative competitive reverse transcription-polymerase chain reaction (RT-PCR) was used to investigate the expression of inhibin/activin subunits in the granulosa cells of developing ovarian follicles of the hen. Two competitors specific to inhibin alpha and betaA subunits were constructed. In one study, the expression of inhibin alpha and betaA genes was determined in the granulosa cells of the five largest yellow follicles (F1, F2, F3, F4/5), the small yellow follicles (SYF), and the large white follicles (LWF) of a layer strain of chickens. Competitive RT-PCR for inhibin alpha subunit revealed 10.35 +/- 2.15 pg/ microg total RNA in the LWF. The expression increased 40-fold in the SYF and remained at that level in the F4/5 but decreased markedly thereafter up to the F1 stage. Inhibin/activin betaA subunit was also detected in the LWF in low amounts and showed no significant increase until the F2 stage. The highest level was found in the F1. The pattern of the mRNA for alpha and betaA subunits in the five largest follicles (F1, F2, F3, F4/5) of a broiler breeder strain of chicken was compared with that in the layer strain. Expression of the alpha subunit was significantly higher in the three largest follicles (F1, F2, F3) of the broiler breeder hens, but only in the F2 for the betaA. The results suggest that inhibin alpha may play an important role in the recruitment and differentiation of follicles and that differences between broiler breeders and layers may have consequences at both the pituitary and ovarian levels.

Activins↗
PubMedDate not supplied

Quantitative evaluation of a comprehensive motion, resolution, and attenuation correction program: initial experience.

BACKGROUND: Tomographic myocardial imaging is widely used in the diagnosis and evaluation of patients with coronary artery disease. However, its specificity remains suboptimal because of attenuation, resolution, and motion artifacts. The purpose of this study was to optimize and assess the value of attenuation, blur, and motion correction of myocardial single photon emission computed tomographic data. METHODS AND RESULTS: Forty-seven studies were selected for analysis to provide 3 patient groups. Group A consisted of 18 patients with a low likelihood of coronary artery disease who were used to construct a quantitative normal database and assess changes in the normal bull's-eye produced by filtering and by attenuation correction. Group B consisted of 13 patients with a high probability of normal results, and group C consisted of 16 patients with coronary artery disease defined on angiography. The effects of attenuation correction, especially in conjunction with RESTORE (a depth-dependent deblurring filter), have been quantitated. Analysis indicates a trend to improved sensitivity and specificity for detecting individual vessel disease in this retrospective study. The motion correction program was successfully applied to 93% of patients but detected significant motion requiring correction in only 11 (24%) patients. CONCLUSION: This preliminary retrospective study indicates a potential for improved myocardial single photon emission computed tomography imaging with the use of attenuation and motion correction together with a restorative deblurring filter. Confirmation by a multicenter study and larger patient numbers remain necessary to assess fully the prospective value of the technique.

Adult↗