Experimentally verified mathematical approach for the prediction of force developed by motor units at variable frequency stimulation patterns.

During normal daily activity, muscle motor units (MUs) develop unfused tetanic contractions evoked by trains of motoneuronal firings at variable interpulse intervals (IPIs). The mechanical responses of a MU to successive impulses are not identical. The aim of this study was to develop a mathematical approach for the prediction of each response within the tetanus as well as the tetanic force itself. Experimental unfused tetani of fast and slow rat MUs, evoked by trains of stimuli at variable IPIs, were decomposed into series of twitch-shaped responses to successive stimuli using a previously described algorithm. The relationships between the parameters of the modeled twitches and the tetanic force level at which the next response begins were examined and regression equations were derived. Using these equations, profiles of force for the same and different stimulation patterns were mathematically predicted by summating modeled twitches. For comparison, force predictions were made by the summation of twitches equal to the first one. The recorded and the predicted tetanic forces were compared. The results revealed that it is possible to predict tetanic force with high accuracy by using regression equations. The force predicted in this way was much closer to the experimental record than the force obtained by the summation of equal twitches, especially for slow MUs. These findings are likely to have an impact on the development of realistic muscle models composed of MUs, and will assist our understanding of the significance of the neuronal code in motor control and the role of biophysical processes during MU contractions.

Model-generated decomposition of unfused tetani of motor units evoked by random stimulation.

Unfused tetani of motor units (MUs) evoked by stimulation at variable interpulse intervals at mean frequencies of 20, 25, 33, 40 and 50Hz were studied using ten functionally isolated fast-type MUs from the medial gastrocnemius muscle of adult Wistar rats. A previously proposed algorithm and computer program for mathematical decomposition of unfused tetani into a series of twitches, representing responses to individual pulses, were used. Analysis of the parameters of the decomposed twitches showed considerable variability in force of successive contractions. These twitches were extremely variable with up to 2-fold higher forces and longer contraction times than a single twitch evoked by one stimulus. However, when the stimulation frequency was decreased, the decomposed twitches became similar to the single twitch with respect to amplitude and contraction time. It was found that the basic contractile parameters of decomposed twitches could be predicted with high accuracy on the basis of the tetanus force level at which the next contraction begins. This analysis of the parameters of decomposed twitches demonstrated that the contractile responses of the muscle fibers to successive action potentials generated by motoneurons are highly variable and depend on the previous MU state.

[The possibilities for predicting the course and outcome in peritonitis patients]. / Vuzmozhnosti za prognozirane khoda i izkhoda ot lechenieto pri peritonitno bolni.

Based on a retrograde study of clinical case material, covering the period 1989-1993, and MPI modification, a coefficient of correlation = 0.661054 and standard error = 0.297438 are calculated for all peritonitis patients, whereas in those where all examination criteria are available the coefficient of correlation = 0.742431 and the standard error = 0.344041. This enables high-degree prognostication, as early as during the operation, of the course and outcome of treatment in each individual patient, and accordingly, resorting to a more aggressive tactics and procedures in the patients at risk.

[Immunological studies of the peripheral blood in endometriosis patients]. / Imunologichni izsledvaniia na perifernata kruv na bolni s endometrioza.

The present facts on immunity system in women with endometriosis are quite contradictory. We investigated 30 women with hystological proven diagnosis, divided into three groups: 1st group-10 women with myoma uteri, 2nd group-10 women with endometriosis, 3rd group-10 women with adnexitis chronica. Control group were 65 healthy women in reproductive age between 24-42 years. It is established, that in the 3 groups cell immunity is oppressed, but more highly expressed in women with endometriosis (Tact and Ttot. p < 0.001). There are not changes in the levels of B lymphocytes, but in the women with endometriosis they are most low. In the 3 groups NBT (Nitro Blue Tetrazolium) is with high values, i. e. there is increased dynamic activity on the neutrophils. The humoral immunity (lg G, lg A, lg M) are within the borders of standard. The results suggest the concept for disturbance of cells immunity in endometriosis.

[Changes in specific and nonspecific immune reactivity in women with a complicated obstetrico-gynecologic status]. / Promiana na spetsifichnata i nespetsifichnata imunna reaktivnost pri zheni s uslozhnen akushero-ginekologichen status.

The immunologic status of some groups of women from the obstetric practice was, studied by using some routine immunologic tests. BT test and C-reactive protein were used in parturients with complicated puerperium. Pregnant women with preserved amniotic sac at tenth lunar month were investigated as well as pregnant women with declared labour activity and ruptured amniotic sac and women with normal pos-partial period and parturients with inflammatory process (complicated puerperium). It was established a statistically significant lowering of active and total T-rosette forming cells and increased level of immunoglobulin G in women with declared labour activity and ruptured amniotic sac. There were lowered values of active T-lymphocytes in parturients with inflammatory complications. The performed studies on these women showed that the usage of BT test and determination of C-reactive protein were indicative methods presenting clear picture of the instant state of the infected organism.

[Autoradiographic study of the proliferative activity of bone marrow, spleen and liver cells in healthy mice and in mice with Rauscher virus-induced erythroleukemia]. / Avtoradiograficheskoe izuchenie proliferativnoi aktivnosti kletok kostnogo mozga, selezenki i pecheni zdorovykh myshei i s éritroleikozom, indutsirovannym virusom Raushera.

Bone marrow, spleen and liver of healthy and erythroleukemic mice have been studied by autoradiography. A peripheral zone, where the most of cells were involved in mitosis, and a central one, where the mitotic index was lower, were established in the bone marrow. Normally a zone of high proliferative activity was found in the subcapsular region of the spleen. Boundaries of such zones in the bone marrow and spleen of erythroleukemic mice disappeared. Most of the cells forming the leukemia infiltrates in the liver are in the phase of DNA-synthesis.

[Light activation of the enzyme ribulose diphosphate carboxylase]. / Aktivirovanie svetom fermenta ribulozodifosfatkarboksilazy.

Some activation mechanisms of RuDP-carboxylase under illumination are considered. It is assumed on the grounds of experimental data that under illumination thylacoid membranes pass from one phase (I) to another (II). Kinetics of this transition is taken as similar to that of surface phase transition of the first kind. It is assumed that the number of enzyme molecules passing from the inactive to active state is proportional to the area of thylacoid membranes in the II phase (as the time function). A change in the stroma determined by the kinetics of transition of thylocoid membranes in the transition process leads to a change of the mean time between two successive catalytic acts of the enzyme activated molecules. The obtained kinetic curve of RuDP-carboxylating reaction in the transition process under illumination coincides with the curve obtained in [1] by expanding the experimental curves of the values of labels 14C, 32P of 3PGA to constituents.

[Kinetics of triphosphoglyceric acid formation in Chlorella pyrenoidosa (in vivo) during alternation of light and darkness]. / Kinetika obrazovaniiaa trifosfoglitserinovoi kisloty v Chlorella pyrenoidosa (in vivo) pri smene svetogovo i temnovogo rezhimov.

On the basis of specific features of carbon reduction cycle in photosynthesis (Kalvin cycle or reduction pentosophosphate cycle) and other processes, in which triphosphoryglyceric acid (3PGA) is an intermediate product, and taking into account the available data concerning the reaction of 3PGA pool of Ch. pyrenoidosa (in vivo) to light-dark disturbances approximate kinetic curves of the value of ribulosodiphosphate (RuDP)--carboxylating reaction product and of other 3PGA accumulations in the chloroplast strom aunder light-dark disturbances. Proceeding from the pecularities of these curves a hypothesis is advanced to the effect of some connection mechanisms of photosynthetic and glycolytic processes of 3PGA production.