The ATP/Mg2+ Balance Affects the Degradation of Short Fluorogenic Substrates by the 20S Proteasome.

Proteasomes hydrolyze most cellular proteins. The standard reaction to determine proteasome activity in cellular lysate or elsewhere contains AMC-conjugated peptide substrate, ATP, Mg2+, and DTT. ATP and Mg2+ are included to maintain 26S proteasome functionality. However, most cellular proteasomes are 20S proteasomes, and the effects of ATP on the turnover of fluorogenic substrates by 20S complexes are largely unknown. Here, we evaluated the effect of ATP alone or in combination with Mg2+ on the degradation of AMC-conjugated fluorogenic substrates by purified 20S proteasomes. Degradation of substrates used to determine chymotrypsin-, caspase- and trypsin-like proteasome activities was gradually decreased with the rise of ATP concentration from 0.25 to 10 mM. These effects were not associated with the blockage of the proteasome catalytic subunit active sites or unspecific alterations of AMC fluorescence by the ATP. However, ATP-induced peptide degradation slowdown was rescued by the addition of Mg2+. Moreover, the substrate degradation efficacy was proportional to the Mg2+/ATP ratio, being equal to control values when equimolar concentrations of the molecules were used. The obtained results indicate that when proteasome activity is assessed, the reciprocal effects of ATP and Mg2+ on the hydrolysis of AMC-conjugated fluorogenic substrates by the 20S proteasomes should be considered.

Health-related quality of life and menstrual problems in adolescents.

AIM: To evaluate whether the health-related quality-of-life (HRQoL) scores would be different for adolescents with menstrual problems as compared to those with normal menstruation after taking into account clinical, socio-demographic and life-style factors. METHODS: The Paediatric Quality of Life Inventory 4.0 scale was used to assess HRQoL in 126 schoolgirls of 16 ± 0.4 years old. The adolescents completed semi-structured questionnaires containing information on social and demographic characteristics, life-style features and menstrual questionnaires that included the following: age of menstruation, menstrual cycle length, duration of production, the number of pads used per day, menstrual pain and drug administration to relieve dysmenorrhea. The menstrual problems were classified into three main groups: dysmenorrhoea, oligomenorrhoea, and heavy menstrual bleeding. Anthropometric measurements were performed by a physician. Medical history was obtained from school medical charts. RESULTS: Ninety-seven (77%) girls had menstrual problems. Dysmenorrhoea (n = 92, 73%) was the most frequent of these, followed by oligomenorrhoea (n = 13, 10.3%) and heavy menstrual bleeding (n = 6, 4.8%). Thirteen (10.3%) girls had combined disorders. A multivariate analysis adjusted for life-style factors found an independent association of any menstrual problems, oligomenorrhoea and dysmenorrhoea with low HRQoL scores in the emotional functioning domain. For adolescents with oligomenorrhoea, an association with low total scale scores was also shown but it did not reach statistical significance. CONCLUSION: The prevalence of menstrual problems is high among schoolgirls. Medical professionals working with adolescents should know that girls with menstrual problems are highly likely to have a poor quality of life, especially those with oligomenorrhoea.

Dynamics, kinetics, and transport properties of the one-dimensional mass-disordered harmonic lattice.

In the present paper we thoroughly investigated the dynamics, kinetics, and the transport properties of the one-dimensional (1D) mass-disordered lattice of harmonic oscillators with the number of particles N < or =5000. The thermostat is simulated by the Langevin sources. Our method is adequate to any 1D lattice with linear equations of motion. Two accurate methods to calculate the temporal behavior of pair correlation functions were developed. The feature of the considered disordered model is an existence of localized states with great relaxation times tau to their stationary states. The exponential growth tau proportional variant exp(N) is observed. A method which allows us to extend the range of computed relaxation times up to tau approximately =(10)300 is suggested. The stationary state is unique. The thermal conduction x has the nonmonotonic character versus N: for the number of particles N < 300 the thermal conduction increases as x proportional variant ln N and reaches the maximal value at N approximately =300. At larger values the decreasing asymptotic is observed: x proportional variant N -alpha, and alpha approximately 0.27. An influence of parameters on the calculated properties was analyzed. Mathematical problems associated with the computation of very large times of establishing the stationary states were extensively studied.