[Effect of acute hypoxia on the mechanical and electrical properties of the isolated skeletal muscles in the last third of chick embryogenesis].

The age-related changes of the contractile and electrical responses of the fast (m. tibialis anterior) and slow (m. soleus) isolated skeletal muscles and their changes under acute hypoxia were estimated during the 16-20 days of the chick embryogenesis. For the first time, the contractile and electrical characteristics of these muscles were described in the specified period of embryogenesis. It was shown that the normalized values of the strength of single and tetanic contractile responses m. tibialis anterior significantly exceed these values for m. soleus. It is shown that the normalized values for the strength of the single and tetanic contractile responses in m. tibialis anterior significantly exceed the values for m. soleus. Using the extracellular microelectrodes (loose patch method) on incubation days 16-17, the slow decaying oscillatory excitation waves were registered in the muscle fibers of m. soleus and m. tibialis anterior, and the extracellular action potentials (APs) were registered in 20% of the investigated muscle fibers in m. tibialis anterior. On the developmental day 20 in fast muscles, the amount of muscle fibers, which were able to generate conductive AP, was about 100%, at the same time, it was about 50% in slow fibers. No significant differences in the amplitude-time characteristics of AP between m. soleus and m. tibialis anterior not observed. Under the results obtained, it is assumed that the muscles fast type principally involve in the chicken embryonic motility in normal and during acute hypoxia in the period of incubation from days 16 to 20. To study the mechanisms of change of muscle contractile responses in hypoxia, the influence of caffeine, insulin and ouabain was investigated. Hypoxia caused the decrease of the force of the muscles contractile responses on all studied stages of embryonic development (16-20 days), but did not impact the value of the contracture response caused by caffeine. Proceeding from this, we can conclude that in our conditions, hypoxia does not affect the functional state of the ryanodine receptors. Muscle treated with insulin and ouabain, significantly reduced sensitivity of the contractile responses to the action of hypoxia. It is assumed that membrane Na+, K(+)-ATPase actively particinates in the hypoxic effects.

[Rhythmical contractile activity of amnion in embryogenesis of reptiles and birds].

Rhythmical contractile activity of amnion accompanies development reptiles and birds in the course of the large part of embryogenesis. These rhythmical contractions are myogenic and spontaneous. The strength, frequency, and character of the amnion contractions change in embryogenesis in a regular way. This type of rhythmical activity is sensitive to many neurotransmitters and external factors. Features of similarity and difference of the amnion rhythmical contractile activity in the reptile and bird embryogenesis are considered. There are discussed a possible functional significance of this rhythmical activity and its participation in response of embryo to external actions, such as temperature fluctuations and acute hypoxia.

[Effect of hypoxia on amnion rhythmic contractions and heart rate in the embryonic European pond turtle Emys orbicularis (Reptilia: Emydidae)].

The effect of acute hypoxia (10% O2 for 30 min) on the rate of amnion rhythmic contractions and heart rate (HR) was studied in two age groups of European pond turtle (Emys orbicularis) embryos, on days 19-27 and 37-43 of incubation (30-40 and 60-70% of the period until hatching). Under the control conditions, the two age groups of embryos did not differ from each other in either parameter. Hypoxia did not affect significantly the amnion contraction rate but decreased the HR. The time course of the HR during hypoxia depended on the embryo age. The mean HR in the first group of embryos was 8% decreased by minutes 10-14 of hypoxia and did not change afterwards; in the second group, it was 18% decreased by minutes 3-8 and then partly or completely restored before the end of hypoxic exposure. It has been assumed that the capacity of European pond turtle embryos for restoring the normal HR when exposed to acute hypoxia during the second half of embryogenesis is related to the development of neurohumoral control mechanisms.

[Treatment of neonatal respiratory distress syndrome with surfactant BL].

The paper presents the results of use of the Russian drug Surfactant BL as part of complex intensive care of respiratory distress syndrome (RDS) in the premature newborn. The drug was used in 45 children (a study group). A control group comprised 52 children with RDS who had undergone a course of therapy before the use of the drug at our clinic. Statistical analysis indicated the practical uniformity of the study and control groups. Particular emphasis was laid on the study of changes in the parameters of blood oxygenation and those of artificial ventilation (AV) regimens in both groups of children. The study demonstrated that in the Surfactant BL-treated patients, blood oxygenation (pO2, A-aDO2, respiratory coefficient) improved much more rapidly and, from the end of the first day of treatment to the termination of therapy in the intensive care unit of a maternity hospital, the mean values of these parameters remained statistically significantly better than those in the controls. In the study group, under AV, insufflated gas FiO2 could be reduced more rapidly and by a large quantity and some other AV parameters "attenuated". Analyzing the outcome of treatment of neonatal infants with RDS has indicated that Surfactant BL has a statistically significant advantage in the positive outcomes of treatment in a group of patients treated with this agent as part of complex intensive care.

[Effect of temperature on the rate of oxygen consumption during the second half of embryonic and early postembryonic development of European pond turtle Emys orbicularis (Reptilia: Emydidae)].

Oxygen consumption by eggs of European pond turtle was determined at two constant incubation temperatures of 25 and 28 degrees C during the second half of embryogenesis. During development at both temperatures, the rate of oxygen consumption initially increased to remain constant during the last quarter of embryogenesis. The difference between the rates of oxygen consumption at these temperatures decreased during the studied period. The coefficient Q10 for the rate of oxygen consumption decreased from 9 to 1.7. At an incubation temperature of 28 degrees C, the changes in the rate of oxygen consumption in response to a short-term temperature decrease to 25 degrees C or increase to 30 degrees C depended on the developmental stage and were most pronounced at the beginning of the studied period. During late embryonic and first 2.5 months of postembryonic development, the rate of oxygen consumption did not significantly differ after such temperature changes. The regulatory mechanisms formed during embryonic development are proposed to maintain the level of oxygen consumption during temperature changes.

[Growth and oxygen consumption in embryonic and early postembryonic development of European pond turtle Emys orbicularis (Reptilia: Emydidae)].

Experiments on developing eggs of European pond turtle (Emys orbicularis) demonstrated S-shaped changes in the rate of oxygen consumption and body weight during embryonic development. The rate of oxygen consumption and weight progressively increased within 70 days after hatching. During embryogenesis, the rate of oxygen consumption decreased. After hatching, it increased but then decreased to a certain level, which remained constant to the end of the studied period. We observed unidirectional changes in oxygen consumption rate during embryonic period and this pattern was maintained after hatching as well. The coefficients of the allometric relationship between oxygen consumption and body weight were a = 0.33 and k = 0.52 during the embryonic period and a = 0.17 and k = 0.89 during the postembryonic period.

Extraembryonic motor activity during the embryogenesis of higher vertebrates.

Extraembryonic rhythmic motor activity in higher vertebrates, along with the intrinsic motor activity of the embryo, is important for the normal development of the embryo. This can have different natures in different classes of amniotes (i.e., motor activities of the amnion, yolk sac, and uterus), but these have similar functional importance. This activity changes reproducibly during the process of embryogenesis, providing the optimum conditions for normal embryo development. During embryogenesis, a system for controlling extraembryonic rhythmic motor activity is also formed. There is a trend for the regulation of this activity to become more complex in mammals as compared with birds. Reptiles have received little study from this point of view. In addition to regular changes in extraembryonic rhythmic motor activity during embryogenesis which depend on the developmental stage of the embryo, motor activity can also change in response to changes in a number of environmental factors (for example, temperature and the gas composition of the air). This demonstrates the possible involvement of embryo-associated extraembryonic motor activity in adapting the embryo to changing environmental conditions and maintaining homeostasis for the development of the embryo itself.

[Extraembryonic motor activity during embryogenesis of higher vertebrates]. / Vnezarodyshevaia dvigatel'naia aktivnost' v émbryogeneze vysshikh pozvonochykh zhivotnykh.

Rhythmic motor activity of the extra-embryo structures as well as the embryo motor activity play a major part in normal development of higher vertebrates. When comparing birds and mammals, a trend towards complication of the motor activity regulation is observed. Reptiles as a class of the vertebrates have not been studied enough in this respect. Apart from the regular changes of extra-embryonic rhythmic motor activity, there are some changes in this activity depending on alterations of environmental factors (temperature, gas composition of air, etc.). The extra-embryonic rhythmic motor activity seems to take part in adaptation of the embryo to changing environmental conditions thus maintaining homeostasis of developing embryo.

[The participation of neurotransmitters in the regulation of the motor activity of the chick embryo amnion]. / Uchastie neirotransmitterov v reguliatsii motornoi aktivnosti amniona kurinogo zarodysha.

The authors' data on time-related changes in the contractile activity of non-innervated smooth muscle amnion of the chick embryo devoid of blood vessels and on involvement of the amniotic fluid neurotransmitters in regulation of the amnion motor activity have been summarized. A scheme of possible mechanism underlying regulation of the spontaneous rhythmic contractile activity of the amnion by two antagonistic neurotransmitters present in the amniotic fluid: serotonin and noradrenalin, which stimulate and inhibit the amnion motor activity, respectively. The results of experiments on successive block of the serotonin and adrenergic receptors by introduction of the corresponding antagonists in the chick embryo amniotic fluid speak in favor of the proposed scheme of humoral regulation of the amnion motor activity. A possible involvement of this humoral mechanism in the inhibitory effect of increased carbon dioxide content of the air on the amnion motor activity has been considered.

Iontophoretic delivery of oligonucleotide derivatives into mouse tumor.

Oligodeoxyribonucleotides (22-mers) were delivered through the skin of C3H mice in the region of a mammary gland tumor by means of iontophoresis. It was shown that the oligonucleotides enter the tumor, cross it, and reach all mouse organs. Electrophoretic analysis of the oligonucleotide extracted from tumor showed that the compounds were delivered in the tissue in the intact state.

[The role of serotonin and noradrenaline in regulating the motor activity of the chick amnion]. / Rol' serotonina i noradrenalina v reguliatsii dvigatel'noi aktivnosti amniona kurinogo zarodysha.

In experiments on chick embryos from various age groups, studies have been made of the effect of a blockader of serotonin receptors--cyproheptadine--and blockader of adrenoreceptors--propranolol--on rhythmic activity of the amnion in vivo after injection of the substances into amniotic fluid. Stimulating effect of propranolol from the 9th to the 19th day of incubation and inhibitory effect of cyproheptadine from the 5th to the 19th day of incubation were revealed. These results indicate the existence of serotonin and noradrenaline in the amniotic fluid of chick embryo. High performance liquid chromatography directly confirmed this conclusion.

[Affinity modification of proteins, binding nucleic acids in mammalian cells, by alkylating derivatives of oligonucleotides]. / Affinnaia modifikatsiia belkov, sviazyvaiushchikh nukleinovye kisloty v kletkakh mlekopitaiushchikh, alkiliruiushchimi prozvodnymi oligonukleotidov.

Using the 32P-labelled alkylating oligonucleotide derivative (pT)16, the oligonucleotide interaction with mammalian cells has been studied. The majority of fibroblastoid cell lines tested in this study (COS-1, vero, L-671, Ag 17-1, CHO, B7) as well as mouse hepatocytes were found to contain proteins specifically interacting with oligonucleotides. Cells of Ag 17-1 and COS-1, apart from the 79 kDa protein specific for all fibroblast lines, contained also a protein with a molecular mass of 83 kDa. In BALB/c mouse hepatocytes the 83 kDa protein is the major oligonucleotide binding protein. Analysis of concentration dependencies of specific modification of receptor proteins in liver cells has made it possible to determine the values of constants for the oligonucleotide derivatives binding to the protein. The binding constant for the alkylating oligonucleotide derivative pT16 and the corresponding phosphothioate oligonucleotide has been found to be equal to 5 x 10(6) M-1.

Interaction of cholesterol-conjugated alkylating oligonucleotide derivatives with cellular biopolymers.

Interactions of oligonucleotide derivatives with mammalian cells and cellular biopolymers have been investigated. The derivatives were oligonucleotides bearing an alkylating 2-chloroethylamino group at the 3'-end and a cholesterol residue at the 5'-terminal phosphate. These compounds are readily taken up by cells and react with cellular DNA, RNA and some proteins which may play a role in delivery of the compounds into cells.

[The effect of temperature on the motor activity of the chick embryo and amnion at 5-14 days of development]. / Vliianie temperatury na dvigatel'nuiu aktivnost' émbriona i amniona kurinogo zarodysha 5--14 sutok razvitiia.

It has been shown that cooling the developing eggs from 37.7 degrees C results cessation of motor activity of the amnion in 5-14-day embryos at 36-33 degrees C, whereas motor activity of the embryo remains unaffected up to 31-26 degrees C. Immobilization of the embryo was observed on cooling up to 22-18 degrees C. The recovery of motor activity after cooling during heating takes place in a reverse order. Embryonic movements are observed at 18-23 degrees C, contractions of the amnion--at 28-33 degrees C. These experiments reveal complete independence of embryonic movements from the amnion. Motor activity of the amnion is related to that of the embryo only between the 8th and the 10th day of incubation.

[Rapid time-resolved fluoroimmunometric analysis of myoglobin]. / Bystryi vremiarazreshennyi fliuoroimmunometricheskii analiz na mioglobin.

High performance quantitative procedure for evaluation of myoglobin in blood serum is developed. The principle of two-site immunometry was used involving monoclonal antibodies against nonoverlapping epitopes of myoglobin molecule. The fluorescent compound containing europium served as a label of the antibody. Modification of the single-step assay enabled to increase the velocity of the assay to about 30 min and simplify it. The assay allowed estimation of myoglobin over a broad range of concentrations from 2 ng up to 1,000 ng/ml. The assay may be recommended for use in clinical practice for express diagnosis of myocardium infarction.