Effect of yohimbine and tetrodotoxin on asymmetric displacement currents of nodes of Ranvier

The indole alkaloid yohimbine (40 microM in the outside solution) is shown to reduce the intramembrane charge transferred by the asymmetric displacement current in the frog Ranvier node by 40%, the sodium permeability being inhibited by more than 90%. However, when tetrodotoxin (0.3 microM) was present in the outside solution, yohimbine inhibited the displacement charge only by a few per cent. The data indicate that the occlusion of the external mouth of Na channel by tetrodotoxin hinders the yohimbine (a lipid-soluble substance) effect on asymmetric displacement currents and supposed to affect Na channels from the membrane lipids and partly from the axoplasm. The possible interaction of Na channel blocking agents which are different both in chemical properties and in the modes of action on Na channels should be taken into consideration in the experiments with asymmetric displacement currents.     

Distribution of hematopoietic stem cells in the mononuclear fraction of human umbilical cord blood]

Specific features of intrathoracic tuberculosis course, outcomes and treatment are outlined for 109 children. In 59 of them tuberculosis was associated with nonspecific respiratory diseases (NRD). 28.8%, 25.4%, 18.6, 27.2% of patients had cystic hypoplasia, chronic hypoplasia, recurrent pneumonia, recurrent bronchitis, respectively. Complicated course of tuberculosis occurred 2 times more frequently in its combination with NRD (71.2%). Destruction and discharge of bacteria were recorded in 49.2 and 47.5% of patients, respectively. Undulating running was 3.4 and side effects 1.6 times more frequent. Tuberculous children with NRD need longer antituberculous therapy using wide-spectrum antibiotics, symptomatic and exercise treatment, massage, surgical intervention if necessary. Complete resolution of lung lesions in NRD children were seen 4.8 times less frequently. In case of late diagnosis 54% of them retained residual changes in the form of lung tissues fibrosis, calcified foci in the lungs and lymph nodes.     

Central modifications of reflex parameters may underlie the fastest arm movements

Descending and reflex pathways usually converge on common interneurons and motoneurons. This implies that active movements may result from changes in reflex parameters produced by control signals conveyed by descending systems. Specifically, according to the lambda-model, a fast change in limb position is produced by a rapid change in the threshold of the stretch reflex. Consequently, external perturbations may be ineffective in eliciting additional reflex modifications of electromyographic (EMG) patterns unless the perturbations are relatively strong. In this way, the model accounts for the relatively weak effects of perturbations on the initial agonist EMG burst (Ag1) usually observed in fast movements. On the other hand, the same model permits robust reflex modifications of the timing and shape of the Ag1 in response to strong perturbations even in the fastest movements. To test the model, we verified the suggestion that the onset time of the Ag1, even in the fastest movements, depends on proprioceptive feedback in a manner consistent with a stretch reflex. In control trials, subjects (n = 6) made fast unopposed elbow flexion movements of approximately 60 degrees (peak velocity 500-700 degrees/s) in response to an auditory signal. In random test trials, a brief (50 ms) torque of 8-15 Nm either assisting or opposing the movement was applied 50 ms after this signal. Subjects had no visual feedback and were instructed not to correct arm deflections in case of perturbations. In all subjects, the onset time of the Ag1 depended on the direction of perturbation: it was 25-60 ms less in opposing compared with assisting load conditions. Assisting torques caused, at a short latency of 37 ms, an additional antagonist EMG burst preceding the Ag1. The direction-dependent effects of the perturbation persisted when cutaneous feedback was suppressed. It was concluded that the direction-dependent changes in the onset time and duration of the Ag1 as well as the antagonist activation preceding the Ag1 resulted from stretch reflex activity elicited by the perturbations rather than from a change in the control strategy or cutaneous reflexes. The results support the hypothesis on the hierarchical scheme of sensorimotor integration in which EMG patterns and movement emerge from the modification of the thresholds and other parameters of proprioceptive reflexes by control systems.     

Liver transplantation for fulminant hepatic failure in the pediatric patient

BACKGROUND: Small-bowel transplantation is an alternative to home parenteral nutrition (HPN) in patients with gut failure. Our aim was to report the indication, diagnosis, morbidity, mortality, and intestinal adaptation in the total cohort of Danish patients receiving HPN at any time during the 5 years between 1 January 1991 and 31 December 1995. The data were analysed against the option of transplantation. RESULTS: HPN was given to 129 patients; 59 (46%) had inflammatory bowel disease (15% died), 26 (20%) had cured cancers (42% died), and 44 (34%) had other diseases (dysmotility, surgical complications, infarcts, and so forth; 27% died). Of these, 60% were new in the HPN program, but only 19% received HPN all 5 years; 31 % had terminated HPN, 19% permanently, and 25% died. Only four deaths were HPN-related. In December 1995, 73 patients were receiving HPN in Denmark, for a prevalence of 13.9 per million, which is the highest in Europe but 10-fold lower than in the United States. CONCLUSIONS: Gut failure was the only indication for HPN in Denmark. Weight loss without gut failure, such as disseminated cancer and acquired immunodeficiency syndrome, was not an indication for HPN. Survival after small-bowel transplantation should be assessed against a sizeable mortality among candidates receiving HPN, and this depends on diagnosis and age. In an HPN population comparable with the Danish, a quarter is likely to die within a period of 5 years, a quarter will terminate HPN, and the others survive with HPN. Small-bowel transplantation can be a lifesaving procedure in the small fraction of foreseeable HPN-related deaths, mainly caused by liver failure. Transplantation will not improve survival in most adult HPN patients, and only an improved quality of life after transplantation justifies this procedure in most HPN patients.     

Effect of perinatal malnutrition on the inactive behavior induced by long-term shock and conditioned analgesia

Inactive behavior in response to long-term inescapable foot shock (IS) and conditioned analgesia were evaluated in adult rats perinatally undernourished. During the IS session, control rats exhibited first a period of vigorous activity and then inactive behavior, during which they accepted the shock more passively. Moreover, when these same animals were subsequently placed in the environment associated with shock application, they showed an increase in the paw lick latency. Conversely, in malnourished rats, this IS schedule induced lower behavioral inactivity and rats failed to develop conditioned analgesia. When undernourished rats were injected with morphine (MOR) before IS exposure, it was observed that both phenomena--inactivity during shock and analgesia conditioned by submission to the shock context--were normalized. A possible alteration in the activation of an opiate process implicated in the stress response in early undernourished rats is suggested.     

Effect of argon on the rate of penetration of hydrogen through kh18N10T steel during ion bombardment

Translated from Atomnaya Énergiya, Vol. 67, No. 1, pp. 52–54, July, 1989.     

Penetration of deuterium from plasma through a nickel membrane

Institute of Physical Chemistry, Russian Academy of Sciences. Translated from Atomnaya énergiya, Vol. 76, No. 2, pp. 145–148, February, 1994.