Spatial perception and vestibulomotor responses in man

A study was made on normal human subjects, using a stabilograph to investigate changes in posture produced in response to transcutaneous galvanic stimulation of the right labyrinth. Results were obtained for different head positions and under the illusion of head and trunk rotation produced by stimulating (vibrating) the gulteus maximus muscle. In the absence of illusion of movement, the direction of the vestibulomotor response was determined by the position of the head in relation to the feed: with the normal head position, the body swayed on a frontal plane, and on a sagittal plane when the heat turned through 90°. Vestibulomotor responses were sagittally oriented, as with real head turning, when illusory head and trunk turning through 90° was produced by vibration. When the illusion of head rotation (in relation to the feet) was not produced by this stimulus, the direction of the postural response was not produced by this stimulus, the direction of the postural response was determined by the real orientation of the head. It is concluded that the spatial perception system plays a major part in controlling spatially oriented vestibulomotor responses.Institute for Research into Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 18, No. 6, pp. 779–787, November–December, 1986.     

Analysis of characters coded for by T-DNA using hybridization between tumorous and normal plant cells

In somatic hybrids between tumourous Nicotiana tabacum (B6S3) and normal mesophyll Atropa belladonna cells, the following traits, directly or indirectly connected with T-DNA gene expression and tumourous growth, were analysed: lysopine dehydrogenase activity (LpDH), shoot suppression, root suppression, ability to grow on media with D-lactose as a sole carbon source and resistance to 2-aminoethylcysteine, 5-bromodeoxyuridine and 5-methyltryptophan. Dominant (semidominant) expression was observed for all but one trait studied, e.g. shoot suppression which behaved as a recessive character.Abbreviations LS-H Linsmaier and Skoog (1965) hormone-free medium - NAA Naphtaleneacetic acid - BAP 6-Benzylaminopurine - 2,4-D 2,4-Dichlorophenoxyacetic acid - 5-BUdR 5-Bromodeoxyuridine - 2-AEC 2-Aminoethylcysteine - 5-MT 5-Methyltryptophan     

Application of macroscopic balances to the identification of gross measurement errors

A systematic method is presented which is capable of both detecting the presence of grossly biased measurement errors and locating the source of these errors in a bioreactor through statistical hypothesis testing. Equality constraints derived from material and energy balances are employed for the detection of data inconsistencies and for the subsequent identification of the suspect measurements by a process of data analysis and rectification. Maximum likelihood techniques are applied to the estimation of the states and parameters of the bioreactor after the suspect measurements have been eliminated. The level of significance is specified by the experimenter while the measurments are assumed to be randomly, normally distributed with zero mean and known variances. Two different approaches of data analysis, batchwise and sequential, that lead to a consistent set of adjustments on the experimental values, are discussed. Several examples based on the fermentation data taken from literature sources are presented to demonstrate the utility of the proposed method, and one set of data is solved numerically to illustrate the computational aspect of the algorithm.     

A modified method of UDS detection in vitro suitable for screening the DNA-damaging effects of chemicals

The UDS induced in cultured FL cells by exposure to chemicals was measured as hydroxyurea-resistant incorporation of 3H-TdR in the acid-insoluble fraction of the 14C-TdR-prelabelled cells synchronized by the combination of arginine starvation and pretreatment with hydroxyurea. The level of UDS is represented by the ratios of 3H/14C radioactivities which are measures of specific activities of 3H. Two direct-acting alkylating agents, MMS and MNNG, a cross-linking agent, mitomycin C, and 3 procarcinogens, B(a)P, AFB1 and cyclophosphamide elicited UDS in the absence or presence of the liver-metabolizing system. Three chemicals of unknown carcinogenicity were also able to induce UDS in this assay system, i.e., bis-(O,O-diethylphosphinothioyl)-disulphide, 4-chlorophenoxy acetic acid (sodium salt) and caramelized malt sugar. With the exception of 4-chlorophenoxy acetic acid, they were also active in the Ames test.     

Airway anesthesia effects on hypercapnic breathing pattern in humans

Minute ventilation (VE) and breathing pattern during an abrupt increase in fractional CO2 were compared in 10 normal subjects before and after airway anesthesia. Subjects breathed 7% CO2-93% O2 for 5 min before and after inhaling aerosolized lidocaine. As a result of airway anesthesia, VE and tidal volume (VT) were greater during hypercapnia, but there was no effect on inspiratory time (TI). Therefore, airway anesthesia produced an increase in mean inspiratory flow (VT/TI) during hypercapnia. The increase in VT/TI was compatible with an increase in neuromuscular output. There was no effect of airway anesthesia on the inspiratory timing ratio or the shape and position of the curve relating VT and TI. We also compared airway resistance (Raw), thoracic gas volume, forced vital capacity, forced expired volume at 1s, and maximum midexpiratory flow rate before and after airway anesthesia. A small (0.18 cmH2O X l-1 X s) decrease in Raw occurred after airway anesthesia that did not correlate with the effect of airway anesthesia on VT/TI. We conclude that airway receptors accessible to airway anesthesia play a role in hypercapnic VE.     

The response of generalized motor activation in man

The effect of short acoustic and photic stimuli on the magnitude of the T- and H-reflexes was investigated in man. Two periods of increase in the amplitude and dispersion of the two test reflexes, disappearing during repetition of the stimulation, were found. Its first component differs from the second in the greater change in the T-reflex and the smaller extinction. The pattern of changes after photic and acoustic stimulation was the same but acoustic evoked a stronger response. The changes discovered are a subthreshold manifestation of the generalized response of motor activation evoked by a wide range of stimuli. It is postulated that its first component is determined by interaction between pyramidal impulses and the motor cortex and the second is due to the efferent volley from the primary cortical projection zones through the reticulo-spinal tract.