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Modelling the control of ovulation and polycystic ovary syndrome (1997)

Chávez-Ross, A. ; Franks, S. ; Mason, H. D. ; [et al.]

Springer

Journal of mathematical biology 36 (1997), S. 95-118

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ISSN: 1432-1416

Keywords: Key words: Ovulation ; Lacker models ; Polycystic ovary syndrome ; PCOS

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Mathematics

Notes: Abstract. The control of ovulation in mammalian species appears to be a highly robust process. The primary mechanism is believed to be competition amongst a group of developing follicles, mediated by a hormonal feedback loop involving in the first instance the pituitary. Successful follicles reach maturity and ovulate, the remainder atrophy and die. A model of this control process has been derived by Lacker and his group. Based on simple qualitative assumptions about the hormonal feedback loop, this is able to reflect many of the basic physiological features of ovulation in mammals. However, a fundamental hypothesis of Lacker’s work is that all follicles are identical and respond to hormonal signals in precisely the same way. Not only is this improbable, but it also leads to several aspects of the model which are qualitatively unrealistic, most notable of these is its inability to accurately model the condition known as Polycystic Ovary Syndrome. This common malfunction of the ovulatory control mechanism accounts for up to three-quarters of cases of anovulatory infertility in humans and its understanding is therefore of considerable medical significance. In this paper we extend the analysis of Lacker’s model to the case of non-identical follicles; this allows us to obtain behaviour much closer to that observed in PCOS patients and to draw some tentative conclusions about the mechanisms underlying this condition.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002850050092

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Analysis of the initial stages of the Thermal Decomposition of 1,4-Butanediammonium Dinitrate (1989)

Quirke, J. M. E. ; Fu, J. ; Hardy, K. A. ; [et al.]

Weinheim : Wiley-Blackwell

Propellants, Explosives, Pyrotechnics 14 (1989), S. 76-81

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ISSN: 0721-3115

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology

Notes: The initial stages of the decomposition of 1,4-butanediammonium dinitrate (BDD) were investigated using a molecular beam sampling time-of-flight-quadrupole mass spectrometer system. Experimental results are consistent with the hypothesis that the compound undergoes dissociation into 1,4-butanediamine and nitric acid. Standard electron impact ionisation and fast atom bombardment mass spectrometric analyses of BDD gave support to the molecular beam study.

Additional Material: 9 Ill.