Showing papers by "University of York published in 1983"

Transmission of conformational change in insulin.

Abstract: Crystal structures of insulin contain molecules that are similar but not identical in conformation. Packed helices move relative to each other, these shifts being accommodated by motions of side-chain atoms arising from small changes in torsion angles. Such low-energy conformational adjustments can accommodate shifts of no more than approximately 1.5 A. This limits the extent to which conformational changes can be dissipated locally, causing their transmission over long distances.

Contextual effects in latent inhibition with an appetitive conditioning procedure

Abstract: In three experiments, rats received presentations of a diffuse 30-sec stimulus (a light) and of food, and their tendency to enter the food tray was monitored. Experiment 1 showed that when the light was made to signal the delivery of food, the response of entering the food tray increased in frequency during the stimulus. The acquisition of this conditioned response to the light was retarded in subjects that had received preexposure to the stimulus. In Experiments 2 and 3, subjects received preexposure to the stimulus, some in the same context as that subsequently used for stimulus-food pairings and some in a different context. Those experiencing the change of context acquired the response more readily. It is argued that these results demonstrate a latent inhibition effect that is attenuated by contextual change.

Evidence for caudate nucleus involvement in an egocentric spatial task: Return from passive transport

Abstract: Potegal (1972) proposed that the caudate nucleus was involved in processing sensory (especially vestibular) cues for egocentric spatial orientation. The purpose of these experiments was to determine the effect of caudate nucleus lesions on a return from passive transport (RPT) task, which has been shown to depend on vestibular input (Miller, Barnett, & Potegal, Note 1). In the first experiment, 18 male rats were trained on RPT. Six then received bilateral posterior caudate lesions, 6 received bilateral control lesions in the dorsal hippocampus, and 6 served as sham-operated controls. Postsurgical retraining revealed deficits in RPT for the caudate group, relative to hippocampal and sham groups. To test the specificity of the caudate lesion effect, a second experiment examined the effect of caudate and hippocampal lesions on an exteroceptive-cue-based spatial task, olfactory trail finding (OTF). Neither posterior caudate lesions nor dorsal hippocampal lesions produced deficits in OTF. These results suggest that the role of the posterior caudate in spatially oriented behavior is restricted to egocentric orientation based on vestibular cues. Since the caudate lesions had no effect on air-righting behavior, any vestibulostriatal contribution to RPT must be separate from the regulation of righting reflexes. This contribution may be mediated via the posterior portion of the caudate. Failure to find an effect of hippocampal lesions on RPT supports the suggestion that hippocampal involvement in spatial behavior may be restricted to memory and mapping of exteroceptive cues (O’Keefe & Nadel, 1978).

Mothers' personal social networks and child maltreatment.

Abstract: The social networks of 32 mothers in families being treated in a hospital-based program for indicated cases of child abuse and neglect were compared to the networks of a demographically comparable control group of 24 mothers whose children were not subject to maltreatment. The clinic mothers were found to be more isolated and more insulated from other people in their -networks. Their isolation reflected a deficiency primarily in their peer connections, and their insularity served to separate their immediate families from their peer connections and from the rest of their families. Child and adolescent maltreatment has become more noticeable to the public in recent years as our information-gathering systems have become more efficient and reports issued have revealed its deleterious effects on children (American Health Association, 1976; American Humane Association, 1978; Konopka, 1975; Straus, Gelles, & Steinmetz, 1980; Child Protective Services, Note 1). Severe maltreatment of children by members of their families is unsanctioned by all social communities. There are cultural differences in disciplinary child-rearing practices that share some of the attributes of violence, as described in Erlanger's (1974) review, but nevertheless, there are limits and standards set by all social groups regulating such behavior and specifying the contexts in which and the extent to which it is permitted. The behavior we are concerned with, child maltreatment severe enough to be indicated by Child Protective Services, falls outside these limits and is considered a problem in every social group. Its persistence within the

The existence and calculation of traffic equilibria

Abstract: The paper considers the assignment problem when there are junction interactions. We give an objective function which measures the extent to which a traffic distribution departs from equilibrium, and an algorithm which (under certain conditions) calculates equilibria by steadily reducing the objective function to zero. It is shown that the algorithm certainly works if the network cost-flow function is monotone and continuously differentiable, and a boundary condition is satisfied.

Observations of the flight behaviour of the army worm moth, Spodoptera exempta, at an emergence site using radar and infra‐red optical techniques

Abstract: . 1 Studies were made in Kenya of the flight behaviour of African armyworm moths which had emerged from areas previously infested with‘gregarious’caterpillars. The use of radar and an infra-red optical detector permitted quantitative, direct observations of the flying moths, over all of their flight altitudes, without disturbing their behaviour. 2 Almost all of the successfully emergent moths climbed to altitudes of several hundred metres above ground level and migrated from the emergence sites. Their migratory flights sometimes started on the night of emergence, but on other occasions the moths remained roosting in trees until dawn, then engaged in short dispersal flights, concealed themselves during the day. and commenced migration in mass flights at dusk the following night. 3 The onset of these‘dusk flights’occurred when the irradiance level fell on average to 2.7 × 10−5Wm−2 nm−1 in the 450–800 nm range (in the photometric units appropriate for human vision this corresponds approximately to 2 lux). The‘dawn flights’began with the first sustained increase in irradiance at dawn, and terminated at the end of dawn twilight. 4 Migratory flight in the strong, easterly winds which usually occurred during the first half of the night resulted in rapid, down-wind displacement to the west. Observations of groups of flying moths passing successively over two radars demonstrated that these migrations could cover at least 20 km. 5 In the second half of the night, winds were usually weak and variable, and up-wind or cross-wind directions of displacement were sometimes observed. 6 Moths were observed to disperse rapidly during their migration, so that the mass influxes which lead to outbreaks must be a consequence of subsequent reconcentration. The importance of meso-scale wind convergence zones in reconcentrating flying moths, and the role of rainfall in inducing descent, and possibly landing, are discussed.

Theories of inflation

Abstract: A survey of the new theories of inflation that have developed over the past two decades in response to the inflationary pressures experienced by Western countries examines the shifting debate from explaining inflation as a "causal" process to explaining its increase as a result of constantly changing expectations.

Parenteral and oral antibiotics in elective colon and rectal surgery. A prospective, randomized trial.

Abstract: Our evaluation consisted of a prospective, randomized clinical trial in a homogenous group of 241 patients undergoing elective colon and rectal resections. A significant decrease in wound infection was found in the patients who received intravenous cefoxitin in conjunction with standard bowel preparation. The infection rate correlated with the type of resection; rectal resections had the highest rate in each study group, but parenteral prophylaxis produced a significantly lower wound infection rate. E. coli and Staph. aureus were the most common bacterial isolates in both groups. B. fragilis was recovered in only two Group A patients, which most likely reflects the exceedingly low recovery rate of anaerobic bacteria in our laboratory. Urinary cultures were positive in a large number of patients and reflect the standard use of Foley catheterization in all patients who undergo resection of the colon or rectum. These data indicate that perioperative prophylactic administration of cefoxitin reduces the wound sepsis rate when combined with oral antibiotics and mechanical bowel preparation in patients undergoing resection of the colon or rectum.

Schistosoma mansoni: migration and attrition of irradiated and challenge schistosomula in the mouse.

Abstract: The fate of irradiated, immunizing cercariae and challenge schistosomula was investigated in mice using a quantitative, histological technique which would appear to be more efficient in estimating parasite numbers in skin and lungs than does the tissue mincing and incubation recovery technique used previously by other workers. There was evidence for slight retardation of irradiated (20 krad.) parasite migration in skin, but death of schistosomula in the skin appeared negligible. It was observed that the majority of irradiated parasites remained in the lungs until at least day 21 after infection, and that most schistosomula observed at this time were dead. In mice immunized with irradiated cercariae there was no evidence of attrition of the challenge infection in the skin. The migration profile of challenge parasites in the lungs of immunized animals was not significantly different from that of normal parasites in the lungs of naive animals. Dead challenge parasites were observed in the lungs but their numbers were not considered great enough to account for the final attrition measured by perfusion. It is suggested that the remainder of the attrition of challenge schistosomula may occur in the systemic and/or hepatic portal circulation.

Multipole N.M.R.: IV. Dynamics of single spins

Abstract: Using a multipole operator basis general formulae are obtained which describe the time evolution of the complete density matrix for a spin of arbitrary magnitude interacting with an electric field gradient in a static magnetic field and subject to a sequence of pure (δ-function) pulses. The evolution under the quadrupole interaction is calculated from general non-equilibrium conditions for I ⩽ 9/2. The physical significance of the results and descriptions of the multiquantum spectra are given along with some results of some two-pulse sequences.

Vestibular involvement in a passive transport and return task

Abstract: Rats were trained to return to a water spout after being passively transported away from it along paths containing a 90-deg turn. Path lengths were successively increased to as much as 132 cm by a modified titration procedure. The task was successfully relearned after enucleation. Subsequent vestibular nucleus damage produced a severe, lasting deficit in this task when compared with the effects of cerebellar cortex lesions. In contrast, the vestibular lesions produced only a mild, transient impairment in an olfactory localization task. The most anterior vestibular lesions also affected air righting.

Errors in proofreading: Evidence for the use of word shape in word recognition

Abstract: Subjects were given a passage to read for meaning while at the same time checking off any misspellings. Critical words in the text were mutilated by either deleting or substituting letters. In half of these mutilations, an ascender in the word was removed, resulting in a large change in the overall shape of the word. In the first experiment, it was found that mutilations involving the substitution of letters were more likely to be noticed than mutilations involving deletions. For both types of mutilation, alterations to word shape were more often noticed than alterations that preserved word shape. When word shape cues were eliminated by using mixed-case stimuli in Experiment 2, the shape effect was abolished. The results are interpreted as evidence for a supraletter feature corresponding to word shape.

Romanticism and the Consumer Ethic: Intimations of a Weber-style Thesis

Abstract: Recognition of the fact that the modern consumption ethic has its origins in the late eighteenth century poses the intriguing question of what cultural forces served to accomplish the rejection of traditional patterns of consumption. Clearly The Protestant Ethic served primarily to inhibit consumption and could not have fulfilled this function. However, following Weber's style of analysis, the `spirit" of modern consumerism is identified as resting upon an attitude of restless desire and discontent coupled with the treatment of consumption as an end-in-itself. Romanticism, conceived of as a cultural movement which introduced the modern doctrines of self-expression and fulfillment, is then

Insulin's structural behavior and its relation to activity.

Abstract: This paper discusses the hypothesis that insulin undergoes a conformational change either before or during its binding to the receptor. The evidence for this is not conclusive but allows us to reconcile the following observations: (1) no chemical modification or deletion of invariant surface residues has abolished the hormone's activity—only reduced its potency. (2) Reduction in potency follows many modifications to different side chains, both variant and invariant. (3) There are insulins with perfectly preserved structure (by the criteria of aggregation, spectroscopy, and x-ray analysis) that have markedly reduced potency. (4) Insulins with disturbed structure still exhibit real, sometimes substantial activity.

Patterns of female sexual arousal during sleep and waking: Vaginal thermo-conductance studies

Abstract: The main objective of this investigation was to ascertain whether there are, in the female, periods of sexual excitation or arousal during REM sleep similar to the cycle of penile erections in the male. In a group of 10 subjects, 21–35, utilizing a thermoconductance method that gives a measure of vaginal blood flow (VBF), we are able to confirm that females manifest cyclic episodes of vascular engorgement during REMPs equivalent to erections in men. They occur with equal frequency (95% of REMPs) but differ in distribution, in greater frequency during NREM sleep, in the shorter duration of individual VBF episodes, and in the less tight linkage of VBF episodes to the REMPs. The increases in VBF, in terms of rises of the recording pen on the graph paper, varied from 10 to 45 mm. In order to ascertain the significance of these increases, we compared these sleep responses with waking VBF responses evoked by nonerotic and erotic stimuli and by masturbation. Only erotic stimuli gave VBF responses, the greatest to the movie and masturbation; these were no greater than the maximum levels attained during sleep, namely 40 to 45 mm. Maximum vascular engorgement is finite in male and female and is limited by anatomy. The fact that VBF REM increases appear to be identical to VBF responses to passive waking erotic stimulation and show similar cardiorespiratory patterns suggests that they, too, are erotic in nature. Additionally, the preliminary results of the waking experiment demonstrate that a very high percentage of VBF REM increases are associated with dreams that contain overt or symbolic sexual content. The results indicate that REM periods with VBF increases have a far greater chance of being associated with sexual dreams than do REMPs or NREMPs with minimal VBF increases.

Gallstone lleus: A diagnostic problem

Abstract: A retrospective review of 24 patients with gallstone ileus from our institutions during the period from 1947 through 1981 has been presented. The study was undertaken in an attempt to refine the diagnosis and treatment of this rare entity. The patients ranged in age from 58 to 84 years, and 19 patients were women. The correct preoperative diagnosis was made in 74 percent of the patients using various combinations of clinical history, plain film roentgenograms, and barium contrast upper gastrointestinal series. After an average preoperative hospital stay of 4.5 days, 23 patients required operation. Wound infection developed in nine patients and resulted in wound dehiscence in two. There were four deaths in the patients over 73 years of age (p less than 0.01). Age was the only factor found to correlate with mortality.

Factor structure of the rutter ‘children's behaviour questionnaire’ in a primary school population in a developing country

Abstract: Summary Data from Rutter's ‘Children's Behaviour’ questionnaire derived from the use of the scale in a developing country suggest that its factor structure is stable over sex and over racial groups. However, when analysis is undertaken on potentially pathological groups, then a more differentiated factor structure is apparent.