Sex steroid metabolism and menstrual irregularities in the exercising female. A review

This article aims to clarify why, and by which mechanisms, exercise may influence the normal menstrual cycle. Therefore, the vast amount of literature on this subject is reviewed and a critical appraisal of the most widespread hypotheses if offered. The strikingly low body mass which frequently accompanies exercise-related menstrual irregularities (ERMI) has led some authors to develop a hypothesis which postulates that a critical percentage of body fat is essential to trigger normal menstruation. The relevance of any reference to anorexia nervosa to support this view lacks consistency: female athletes differ in many ways from patients with anorexia nervosa, not least in their excellent physical status which is essential to deliver first-class performances. ERMI is not identical to the so-called female athlete triad, a complicated pathology that involves ERMI, premature osteoporosis and disordered eating. ERMI itself does not seem to have any substantial pathological effects as long as attention is paid to preventing osteoporosis or stress fractures which may result from prolonged hypo-estrogenaemia. In the female athlete with ERMI who wishes to conceive, the accompanying subfertility may necessitate a response other than a prompt reduction in training intensity, as this is hardly a first choice for any top athlete. During recent years, a number of prospective studies have greatly contributed to our understanding of the complexity of the mechanisms involved in ERMI. Older hypotheses, such as those considering hyperprolactinaemia as the cornerstone of ERMI, have now been firmly rejected. The present hypotheses emphasise the importance of caloric deficiency and limited energy availability, although they still fail to identify the actual mechanism that causes ERMI. There is, however, evidence that ERMI is produced by a disturbance of the hypothalamic gonadotrophin-releasing hormone oscillator. This disturbance is caused by either an insufficient estrogen or progesterone feedback or by an imbalance of local opioid peptide and catecholamine activities mediated by gamma-aminobutyric acid (GABA), corticotrophin-releasing hormone and insulin-like growth factor-1. More recent experiments have also linked ERMI with changes in steroid metabolism, in particular, an increasing activity of catecholestrogens possibly leading to enhanced intracerebral noradrenaline (norepinephrine) levels that may interfere with normal gonadotrophin release. This article demonstrates that the outcome of the many studies of ERMI is characterised by much controversy and numerous methodological flaws. The importance and complexity of some recent findings necessitate a comprehensive study which links older and newer findings within a critical perspective.     

Detection of glomus tumor of the finger by dedicated MRI at 0.1 T

Three glomus tumors of the fingers were detected using a dedicated hand and wrist low field (0.1 T) MR imager equipped with solenoidal coils allowing a FOV of 2 cm. Three-dimensional T1-, T*2-, or T2-weighted images were used (8 contiguous slices of 2 mm thickness). Glomus tumors had low or intermediate signal intensity (2 cases) or no signal (1 case) on T1-weighted images. On T*2- or T2-weighted images they had high signal intensity. MRI findings correlate well with surgery and biopsy.     

Interval analytic treatment of convex programming problems

A nonlinear convex programming problem is solved by methods of interval arithmetic which take into account the input errors and the round-off errors. The problem is reduced to the solution of a nonlinear parameter dependent system of equations. Moreover error estimations are developed for special problems with uniformly convex cost functions.     

Pattern-recognition properties of r.a.m./r.o.m. arrays

Arrays of r.a.m.s may be used as trainable logic devices in arrays whose object is to recognise patterns. The way in which such a system is organised is presented and some of the characteristics of the nature of the recognition are discussed     

Behaviour of Composite Ca/P Bioceramics in Simulated Body Fluid

Behavior of Ca/P ceramics enhanced by MgAl2O4 in simulated body fluid(SBF) was studied.Results show that, biological apatite can precipitate on the sudece of Ca/P composite ceramics,however, dissolution of the surface of Ca/P composite ceramics also occurs due to a kind of amorphous material which is produced through reaction of MgAl2O4 with Ca/P ceramics at elevated temperature, therefore, the behavior of Ca/P composite ceramics in SBF mainly depends on those two processes. Analyses of joint influence of those two processes show that low content of MgAl2O4 favors the formation of biological apatite, therefore, brings about higher bioactivity     

Behavioral control of exercise in sedentary adults: Studies 1 through 6.

Conducted 6 experiments with 143 healthy sedentary adults who had been unsuccessful in starting or maintaining an exercise regimen to identify behavioral and cognitive procedures that would enhance Ss' adherence to a 3 day/wk exercise (walking/jogging) program. Procedures evaluated included feedback and praise during exercise, various goal-setting strategies, lottery reinforcement, cognitive strategies during the exercise, and relapse-prevention training. Class attendance, exercise program adherence, and fitness data were collected, and self-reported 3-mo follow-up data were also obtained. Results suggest the importance of social support, feedback, and praise during exercise; flexibility in exercise-goal setting; and distraction-based cognitive strategies. Findings are integrated and discussed in terms of the importance and difficulties of shaping and maintaining exercise behaviors. (58 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Utilisation de l'algue oocystis sp. Pour le traitement tertiaire des eaux usees-II. Effet du conditionnement prealable des cellules en cyclostat sur leur vitesse de prise en charge de l'azote lors d'incubations de longue duree

In an attempt to examine if the rapid uptake of nitrogenous nutrients by “starved” cells occurs also during the prolonged incubation required for complete removal of nutrient from wastewater, ammonia uptake rates for Oocystis sp., in preconditioning phase (phase I) and incubation phase (phase II) are compared.When equilibrium is reached in phase I, phytoplankton cells have a relatively constant N-ammonia uptake rate per cell; this rate varies with the different water stocks used in different experiments, but it is always lower (2–6 times) than the uptake rate exhibited by these cells in phase II.At the end of the second phase (12 h) the cell nitrogen content is up to 3.5 times higher than the initial content.These characteristics of alga Oocystis sp. are discussed and commented.     

Antiproton-proton mass comparison with a radio-frequency mass spectrometer

The experiment aims at the reduction of the upper limit on a hypothetical CPT violation in the antiproton-proton system. A radio-frequency mass spectrometer (RFMS) has been designed and built to make the comparison of the charge to mass ratios of and p by measuring the ratios of the cyclotron frequencies of and H⁻ ions. At present, the RFMS is installed on-line to the LEAR facility at CERN. The resolving power has been found to be close to 3 × 10⁵ and it still could be improved. A decelerating system (RFQ) has been installed in order to decelerate antiprotons from 2 MeV to 200 keV and to match as well as possible the acceptance of the spectrometer. It is presently under test and data taking should take place in 1992.