Channel-forming action--a general property of venoms of spiders in the family Theridiidae (Aranei)

The study of venom action of 10 spider species of Theridiidae family has shown that they cause the formation of the cation selective channels on the bilayer lipid membranes. This action does not depend on the species sex and age and it is the important diagnostic characteristic of the family. The channel-forming effect is due to the presence of the peptide with molecular weight about 5000 daltons in venoms of Theridiidae spider family.     

Transplantation of embryonic nerve tissue from the preoptic region: Effects on coordination of ovarial,locomotor, and temperature biorhythms in rats

Motor activity and changes in body temperature related to the alternation of stages of an estrous cycle were studied in albino rats; groups of animals with the intact preoptic region (RPO), with electrolytically destroyedRPO, and with lesion of this structure followed by a transplantation of the embryonicRPO tissue were compared. It is hypothesized that the changes in hormonal background level related to the stages of estral cycles and controlled with the involvement of theRPO determine the amplitude of infradian cyclic variations of motor activity and body temperature, but do not initiate these rhythms.Neirofiziologiya/Neurophysiology, Vol. 26, No. 4, pp. 283–290, July–August, 1994.     

Responses of neurons of the preoptic region to an increase in systemic blood pressure in cats

Responses of neurons of the lateral and medial parts of the preoptic regionRPO (LPO andMPO, respectively) and the supraoptic nucleus (SO) of the hypothalamus to an increase in systemic blood pressure were studied in acute experiments on ketamine-anesthetized cats. The blood pressure increase resulted from the injection of a 0.002% phenylephrine hydrochloride solution in the femoral vien. Responses of theRPO neurons to suprathreshold pressor stimulation were monophasic activation (48% of units), monophasic inhibition (10%), or two-phase activational-inhibitory complex (14%). The rest of the neurons did not respond to the systemic pressure increase. Pressor stimulations evoked the responses only of the first and third type inMPO neurons, and only of the first and second type inLPO neurons, whileSO neurons generated responses only of the first type. Hysteresis of a varying degree was manifested in the changes of neuronal spike activity accompanying shifts of the systemic pressure. In some neurons there was no strict correlation between the pressor effect and the onset of neuronal response. Osmosensitivity of a part of neurons was tested. The responses of most of theRPO andSO neurons to pressor influences and infusions of hypertonic saline were of similar direction, whereas responses to infusions of hypotonic saline were opposite.Neirofiziologiya/Neurophysiology, Vol. 26, No. 2, pp. 132–140, March–April, 1994.     

Polypharmacy in the management of patients with schizophrenia on risperidone in a tertiary-care hospital in Malaysia

The present study was conducted primarily to determine the occurrence of polypharmacy in patients with schizophrenia on risperidone. The secondary aim was to ascertain the incidence of inappropriate prescribing with anticholinergics. A retrospective review of the medical records of all patients who were being followed up at the out-patient clinic of a tertiary-care hospital in Malaysia was conducted. Only patients who were being prescribed risperidone between 1 June 2008 and 31 December 2008 were included in the study. Demographic data such as patient’s age, gender and race were obtained from the patient’s medical records. In total, 113 patients met the selection criteria. Polypharmacy was found to occur in 34 patients (30.09%), with the majority (76.47%) being on two antipsychotics. In total, 27 patients (34.18%) on monotherapy with risperidone were prescribed an anticholinergic on scheduled dosing, while 19 patients (24.05%) were prescribed it on an as-needed basis. Of the patients on polypharmacy, 26 (76.47%) were on scheduled dosing of anticholinergics, while three (8.82%) were taking the medication on an as-needed basis. Polypharmacy should be avoided, and the use of anticholinergics should be closely reviewed. By adopting more efficient prescribing practices, costs can be reduced and financial resources can instead be channelled towards more beneficial areas for the patients.     

X-pinch-based neutron source

Results are presented from experimental studies of the parameters of an X-pinch-based neutron source made of 70- to 80-μm-diameter deuterated polyethylene fibers. At currents of up to 1.7 MA and a current rise time of ～150 ns, hot plasma spots were observed in the fiber crossing region. The formation of hot spots was accompanied by the generation of short soft X-ray pulses with a duration of 2–4 ns, as well as by neutron emission. The neutron energy was measured using the time-of-flight technique in four directions, at 0°, 90°, 180°, and 270° with respect to the load axis. The mean energy of the neutrons emitted along the axis towards the anode and cathode was found to be 2.0 ± 0.2 and 2.6 ± 0.1 MeV, respectively, and that of neutrons emitted in two opposite directions along the radius, 2.5 ± 0.1 and 2.4 ± 0.1 MeV. The maximum neutron yield at a current amplitude of 1.6 MA was of 10¹⁰ neutrons per shot.     

Effect of aceclidine and fenazepam on the indices of humoral immunity and nonspecific resistance of the body after immunization with a chemical typhoid vaccine

Phenazepam (2.5 mg/kg) and aceclidine (4 mg/kg), when introduced in a single injection at the inductive phase of immune response, enhance the production of antibodies after immunization with chemical typhoid vaccine. The combined use of these preparations has been to produce a potentiating effect.     

Role of the diencephalic preoptic region in coordination of thermoregulatory and nutrition-related reactions

In acute experiments on cats we studied convergence of the afferent temperature-related and glycemic signals on the neurons of the preoptic region (RPO1). Local heating and cooling (±7°C) of the skin on the contralateral forelimb pad were used for identification ofRPO neurons as thermosensitive units, while infusion of 0.1–0.4 ml of 5.5% glucose solution in the ipsilaterala. carotis revealed their sensitivity to shifts in the glucose concentration. More than half (57%) of glucosensitiveRPO neurons responded to the changes in peripheral temperature. The pattern of convergence and peculiarities of localization of the convergent neurons were studied. We propose the following hypothesis:RPO neurons receiving convergent thermal and glycemic inputs provide formation of integral controlling signals addressed to the ventromedial and lateral hypothalamic nuclei, which control the thermoregulatory food consumption.     

Transportation properties of a high-current magnetically insulated transmission line and dynamics of the electrode plasma

Results are presented from experimental studies of a section of a magnetically insulated transmission line (MITL) with a current density of up to 500 MA/cm² and linear current density of up to 7 MA/cm (the parameters close to those in a fast-Z-pinch-driven fusion reactor projected at Sandia Laboratories). The experiments were performed in the S-300 facility (3 MA, 0.15 Ω, 100 ns). At high linear current densities, the surface of the ohmically heated MITL electrode can explode and a plasma layer can form near the electrode surface. As a result, the MITL can lose its transmission properties due to the shunting of the vacuum gap by the plasma produced. In this series of experiments, the dynamics of the electrode plasma and the dependence of the transmission properties of the MITL on the material and cleanness of the electrode surface were studied. It is shown experimentally that, when the current with a linear density of up to 7 MA/cm begins to flow along a model MITL, the input and output currents differ by less than 10% over a time interval of up to 230 ns for nickel electrodes and up to 350 ns for a line with a gold central electrode. No effect of the oil film present on the electrode surface on the loss of the transmission properties of the line was observed. It is also shown that electron losses insignificantly contribute to the total current balance. The experimental results are compared with calculations of the electrode explosion and the subsequent expansion of the plasma layer. A conclusion is made that the life-time of the model MITL satisfies the requirements imposed on the transmission lines intended for use in the projected thermonuclear reactor.