High performance liquid chromatography of nucleic acids and the related compounds on a fluorinated silica gel column.

Separations of nucleic acids and the related compounds were investigated by HPLC on a new fluorinated bonded silica gel column. Polyadenylate (Poly (A)) enzymatic partial hydrolysate sample and the mixture of various polynucleotide samples were sufficiently separated by the reversed-phase mode using a gradient elution with aqueous ammonium acetate/acetonitrile system. Mixed-mode separation on the fluorinated bonded phase coated with a tert-alkylammonium salt was also examined for the separation of the various polynucleotides including tRNAs.     

The effect of age on the maximum moments of strength of the muscles of the lower extremities in patients with lumbar disc hernia

The maximum contractility of the muscles of the lower extremities was studied in patients with lumbar disc hernia in different age periods. Characteristics of the age-related changes in the muscle function of the patients were analyzed in comparison with the parameters of men with physiologically normal aging. It is shown that the maximum strength of muscles of the lower extremities (lower leg extensors and flexors and plantar flexors of the foot) in patients with lumbar disc hernia is 46–50% lower than in healthy subjects. This value is characterized by a negative correlation with age. The percentage of the age-specific decrease in the strength of three groups of muscles (lower leg extensors and flexors and plantar flexors of the foot) is 14% higher than in healthy men. The age-related decrease in the muscle strength of the lower extremities begins 30 years earlier.     

The development of the epidemic process and the formation of humoral immunity to the hepatitis A virus in adolescent collectives

Additional observation on the formation of humoral immunity to hepatitis A virus has been carried out in 2,375 adolescents aged 15-17 years and belonging to 12 groups at 3 areas of the USSR. This observation has shown that in the presence of a high level of the immune stratum the spread of infection occurs, as a rule, outside the group under observation. Besides, as revealed in this study, the risk of seroconversion and the loss of specific antibodies are, respectively, directly and inversely related to the level of the immune stratum in the group. The level of the immune stratum in a given age group supposedly reflects the intensity of the development of the epidemic process at a definite area.     

The effect of tetrodotoxin on the sodium gating current in the squid giant axon.

The effect of tetrodotoxin (TTX) on the sodium gating current in the squid giant axon was examined by recording the current that flowed at the pulse potential at which the ionic current fell to zero, first in the absence and then in the presence of TTX. The addition of 1 microM TTX to the bathing solution had no consistent effect on the size of the initial peak of the gating current, but resulted in small changes in the timecourse of its subsequent relaxation which were mainly caused by a reduction of about one quarter in the component that has a delayed onset and may possibly arise from changes in the state of ionization of groups in the channel wall when the lumen fills with water. Our findings suggest that the binding of TTX at the outer face of the sodium channel does not interfere with the mechanisms of activation and inactivation by the voltage sensors, but has an allosteric effect on the access of internal cations to the inside of the channel.     

Activation of TIMP-2/progelatinase A complex by stromelysin.

Progelatinase A was purified as a complex with TIMP-2 from the conditioned medium of a human glioblastoma cell line. The TIMP-2/progelatinase complex was resistant to the activation by p-aminophenylmercuric acetic acid (APMA), and showed less than 10% of the activity of the TIMP-2-free active enzyme. When the complex was incubated with stromelysin in the presence of APMA, the 64-kDa progelatinase was effectively converted to the 57-kDa mature enzyme, increasing its gelatinolytic activity about 8-fold. These results suggest that stromelysin is a natural activator of TIMP-2-bound progelatinase A.     

Neuropeptide cycloprolylglycine increases the levels of brain-derived neurotrophic factor in neuronal cells

It was shown for the first time that the endogenous cyclic dipeptide cycloprolylglycine (CPG) at concentrations of 10^–7 and 10^–3 M and piracetam at a concentration of 10^–3 M increased the content of brainderived neurotrophic factor (BDNF) in the culture of neuronal cells in normal state and under conditions of glutamate and 6-oxydopamine neurotoxicity. This may indicate the possible involvement of BDNF in the mechanism of action of neuropeptide CPG and piracetam.     

Organization of reflex sympathetic influence on rate and force of cardiac contraction]

In acute experiments on 21 cats it was proved that the change of afferent impulse on vagus nerves by means of either freeze-block or electrostimulation of their central ends results in differential reflex influences on rhythm and force of the cardiac contractions caused by sympathetic nervous system. The cut of the lower cardiac nerves may cause 'break-up' of the observed reflex, removing or inverting its ino- or chronotropy component. The given phenomenon was revealed in the experiments with high arterial pressure and with absence of tonic chronotropy influences of the left lower cardiac nerve.