Showing papers by "Virginia Commonwealth University published in 1987"

A fluid percussion model of experimental brain injury in the rat

Abstract: Fluid percussion models produce brain injury by rapidly injecting fluid volumes into the cranial cavity. The authors have systematically examined the effects of varying magnitudes of fluid percussion injury in the rat on neurological, systemic physiological, and histopathological changes. Acute neurological experiments showed that fluid percussion injury in 53 rats produced either irreversible apnea and death or transient apnea (lasting 54 seconds or less) and reversible suppression of postural and nonpostural function (lasting 60 minutes or less). As the magnitude if injury increased, the mortality rate and the duration of suppression of somatomotor reflexes increased. Unlike other rat models in which concussive brain injury is produced by impact, convulsions were observed in only 13% of survivors. Transient apnea was probably not associated with a significant hypoxic insult to animals that survived. Ten rats that sustained a moderate magnitude of injury (2.9 atm) exhibited chronic locomotor deficits that persisted for 4 to 8 days. Systemic physiological experiments in 20 rats demonstrated that all levels of injury studied produced acute systemic hypertension, bradycardia, and increased plasma glucose levels. Hypertension with subsequent hypotension resulted from higher magnitudes of injury. The durations of hypertension and suppression of amplitude on electroencephalography were related to the magnitudes of injury. While low levels of injury produced no significant histopathological alterations, higher magnitudes produced subarachnoid and intraparenchymal hemorrhage and, with increasing survival, necrotic change and cavitation. These data demonstrate that fluid percussion injury in the rat reproduces many of the features of head injury observed in other models and species. Thus, this animal model could represent a useful experimental approach to studies of pathological changes similar to those seen in human head injury.

Determinants of multisensory integration in superior colliculus neurons. I. Temporal factors.

Abstract: One of the most impressive features of the central nervous system is its ability to process information from a variety of stimuli to produce an integrated, comprehensive representation of the external world. In the present study, the temporal disparity among combinations of different sensory stimuli was shown to be a critical factor influencing the integration of multisensory stimuli by superior colliculus neurons. Several temporal principles that govern multisensory integration were revealed: (1) maximal levels of response enhancement were generated by overlapping the peak discharge periods evoked by each modality; (2) the magnitude of this enhancement decayed monotonically to zero as the peak discharge periods became progressively more temporally disparate; (3) with further increases in temporal disparity, the same stimulus combinations that previously produced enhancement could often produce depression; and (4) these kinds of interactions could frequently be predicted from the discharge trains initiated by each stimulus alone. Since multisensory superior colliculus neurons project to premotor areas of the brain stem and spinal cord that control the orientation of the receptor organs (eyes, pinnae, head), they are believed to influence attentive and orientation behaviors. Therefore, it is likely that the temporal relationships of different environmental stimuli that control the activity of these neurons are also a powerful determinant of superior colliculus-mediated attentive and orientation behaviors.

Tryptase Levels as an Indicator of Mast-Cell Activation in Systemic Anaphylaxis and Mastocytosis

Abstract: Better methods are needed to assess mast-cell activation in vivo and to distinguish the activation of mast cells from that of basophils. Tryptase, a neutral protease selectively concentrated in the secretory granules of human mast cells (but not basophils), is released by mast cells together with histamine and serves as a marker of mast-cell activation. In 17 patients with systemic mastocytosis, concentrations of tryptase in plasma were linearly related to those of histamine (P less than 0.01). Eleven of the 17 patients had tryptase levels of 4 to 88 ng per milliliter, indicating ongoing mast-cell activation. In each of six patients who experienced corresponding anaphylactic reactions after penicillin, aspirin, or melon ingestion, a wasp sting, exercise, or antilymphocyte globulin injection, tryptase levels in serum ranged from 9 to 75 ng per milliliter, indicating mast-cell activation during each of these events. In contrast, serum tryptase levels were less than 5 ng per milliliter in all patients presenting with myocardial disease (n = 8, 6 with hypotension) or sepsis (n = 6, 3 with hypotension) and in the controls (n = 20). One patient had a myocardial infarction after anaphylaxis in response to a wasp sting and an elevated tryptase level of 25 ng per milliliter. Thus, the plasma or serum tryptase level is a diagnostic correlate of mast-cell-related events.

The eyes have it: lexical and syntactic comprehension in a new paradigm.

Abstract: A new method to assess language comprehension in infants and young children is introduced in three experiments which test separately for the comprehension of nouns, verbs, and word order. This method requires a minimum of motor movement, no speech production, and relies on the differential visual fixation of two simultaneously presented video events accompanied by a single linguistic stimulus. The linguistic stimulus matches only one of the video events. In all three experiments patterns of visual fixation favour the screen which matches the linguistic stimulus. This new method may provide insight into the child's emerging linguistic capabilities and help resolve longstanding controversies concerning language production versus language comprehension.

Identification of glucocorticoid-inducible cytochromes P-450 in the intestinal mucosa of rats and man.

Abstract: We used monoclonal antibodies and complementary DNAs (cDNAs) to glucocorticoid-inducible liver cytochromes P-450 in rats (P-450p) and in man (HLp) to search for related cytochromes in intestinal mucosa. In rat enterocytes, we found two dexamethasone-inducible proteins related to the steroid-inducible liver cytochromes P-450. Induction of these proteins in enterocytes was associated with increases in the amount of a P-450p-related messenger RNA and of erythromycin demethylase, an activity highly characteristic of P-450p and HLp. Similar studies on human jejunal enterocytes revealed a microsomal protein indistinguishable from HLp on immunoblots and an abundance of RNA hybridizing with HLp cDNA. In human enterocytes the specific concentration of the HLp-related cytochrome (measured immunochemically or as erythromycin demethylase activity) was similar to that found in human liver and could account for all of the CO-binding hemo-protein detected. We conclude that the intestinal mucosa contains prominent form(s) of cytochromes P-450 similar to liver cytochrome P-450p in their structure, function, and some regulatory characteristics.

Bacteriology of Human Gingivitis

Abstract: The subgingival bacterial floras of naturally occurring gingivitis in adults and children were characterized and compared with the floras of other periodontal conditions previously studied. The composition of the gingivitis floras was found to be distinct from that of floras associated with health or with moderate, severe, or juvenile periodontitis. There were no major differences between the floras of naturally-occurring gingivitis and the floras of the human experimental gingivitis model. Data indicated that the flora of healthy sites within a mouth is influenced by the number of inflamed sites, which argues against independence of sites bacteriologically. Proportions of ten bacterial species increased in both gingivitis and periodontitis, as compared with health, in both adults and children. These species were found in both affected and unaffected sites of people with gingivitis. The numbers of five other cultivable species and the "large treponeme", which was not cultivated, increased in gingivitis and periodontitis of adults only. Significant differences in non-spirochetal floras between children and adults were not found, although they were in the experimental gingivitis model studied previously. Cultivable spirochetes did differ between children and adults. Children had fewer samples positive for spirochetes, and children's positive samples contained greater proportions of T. socranskii subsp. paredis. Some species that predominate in periodontitis, but which are absent from healthy gingivae, were found as a small percentage of the flora in gingivitis. This suggests that increased serum and blood in the gingival crevice encourage species that relate to periodontitis.

Enhancing college students' critical thinking: A review of studies

Abstract: Twenty-seven studies are reviewed that investigate the effect of instructional methods, courses, programs, and general college experiences on changes in college students' critical thinking. Only two studies used true experimental designs; most were nonequivalent pretest-posttest control group designs. The results failed to support the use of specific instructional or course conditions to enhance critical thinking, but did support the conclusion that college attendance improves critical thinking. What is lacking in the research is a common definition of critical thinking, good instrumentation to provide specific measurement, and a clear theoretical description of the nature of an experience that should enhance critical thinking.

Changes in Supervision as Counselors and Supervisors Gain Experience: A Review

Abstract: Evidence bearing on whether and how counselors and supervisors receive or give different types of supervision of psychotherapy as they each gain experience was investigated. Theories describing changes in supervision of counselors as they gain experience are reviewed. Most are similar to each other. They posit changes in the supervisee, with supervision environments being matched to the changing needs of the supervisee. There are three theories concerning how the supervisor changes as he or she gains experience. Findings from empirical studies are consistent with theories of counselor development but only weakly supportive of the theory that actual supervision environments are matched to supervisee needs. Findings from empirical research on changes in supervisors as they gain experience reveal few differences in supervisors at any level beyond the master’s degree. Presumably, therapists and supervisors age like wine. In this article, I sample their sounds, sights, bouquets, and tastes as they gain experience. Supervision of prepracticum counselors is not covered in this review (for a recent review, see Kurtz, Marshall, & Banspach, 1985). Rather, this article is a summary of supervision of counselors from their first practicum and beyond. First, the issue of what supervision should be is discussed. Then research on changes in supervision as counselors gain experience is reviewed. Last, research on changes in supervision as supervisors gain experience at supervision is examined.

Contribution of CSF and vascular factors to elevation of ICP in severely head-injured patients.

Abstract: ~," The authors studied the relative contribution of cerebrospinal fluid (CSF) and vascular parameters to the level of intracranial pressure (ICP) in 34 severely head-injured patients with a Glasgow Coma Scale score of less than 8. This was accomplished by first characterizing the temporal course of CSF formation and outflow resistance during the 5-day period postinjury. The CSF formation and outflow resistance were obtained from pressure responses to bolus addition and removal of fluid from an indwelling ventricular catheter. The vascular contribution to the level of ICP was assessed by withdrawing fluid at its rate of formation and observing the resultant change in equilibrium ICP level. It was found that, with the exception of patients with subarachnoid hemorrhage, CSF parameters accounted for approximately one-third of the ICP rise after severe head injury, and that a vascular mechanism may be the predominant factor in elevation of ICP.

Cognitive, affective, and behavioral effects of reminiscence group therapy on demented elderly.

Abstract: Twenty-seven demented elderly nursing home residents were given either reminiscence group therapy or supportive group therapy or were assigned to a no-treatment control group. The self-reported level of depression in participants given reminiscence therapy was positively affected compared to participants in the supportive therapy and control groups, but no significant effects were found for cognitive or behavioral functioning. Results are discussed in terms of the issue of the applicability of reminiscence therapy for cognitively impaired persons, the appropriateness of the measures used in this study to assess depression, cognitive ability and behavioral functioning, and in conjunction with clinical observations made during the process of therapy.

Pressure-volume index in head injury

Abstract: The authors studied intracranial pressure (ICP) and intracranial compliance as defined by the pressure-volume index (PVI) in 34 severely head-injured patients with a Glasgow Coma Scale score of 8 or less. The objective of the research was to determine if there was a correlation between the pressure-volume status and subsequent increase in ICP. The PVI and ICP measurements were obtained serially, and the temporal course of the pressure-volume status and ICP was determined during the 5-day period following injury. Aggressiveness of ICP was quantified by a therapy intensity level scale. A clear relationship between the PVI measured soon after injury and subsequent development of ICP emerged. Following mechanical trauma the PVI is reduced, and the degree of reduction and extent of biomechanical recovery are closely related to outcome and development of raised ICP.

The illusion of intimacy television and the role of candidate personal qualities in voter choice

Abstract: The role of television in the increased candidate orientedness of voters in U.S. presidential elections was examined using data from eight National Election Studies conducted by the Survey Research Center at The University of Michigan. The importance of candidate personal qualities and traits was estimated using voter responses to open-ended questions about the candidates. Candidate personal qualities became more important for television dependent voters during the 1960s, and in each post-1964 election were less important for voters who relied on newspapers than for those who relied on television. The differences did not appear to be a function of the higher level of education of newspaper readers. The availability of over thirty years of carefully collected survey data has made possible the study of change in how voters choose among presidential candidates. An important finding of studies utilizing these data is the increased importance of candidate personal qualities (see, among others, Popkin et al., 1976; and Kirkpatrick et al., 1975). Coincident with this change has been the birth and development of television, now the most widely used medium of political information. This paper examines the role of television in the increased candidate-orientedness of the public, and offers empirical support for the proposition that television has facilitated and encouraged vote choices based upon the personal qualities of candidates. Television's potential for affecting the criteria of choice in elections was noted from the start. Looking ahead to the first "TV election," Jack Gould, television critic for the New York Times, wrote in the summer of 1952 that SCOTT KEETER is Director of the Commonwealth Poll in the Survey Research Laboratory, and Assistant Professor of Political Science at Virginia Commonwealth University. The data were made available by the Inter-university Consortium for Political and Social Research, which bears no responsibility for the analysis and interpretation presented here. The author wishes to thank John Brigham, William Gormley, Gerald Pomper, and this journal's anonymous reviewers who commented upon earlier drafts. Public Opinion Quarterly Volume 51:344-358 ?) 1987 by the American Association for Public Opinion Research Published by The University of Chicago Press / 0033-362X/87/0051-00/$2.50 This content downloaded from 207.46.13.115 on Sat, 08 Oct 2016 05:08:45 UTC All use subject to http://about.jstor.org/terms Candidate Personal Qualities and Voter Choice 345 a TV-aware electorate is not going to be voting for a man merely on the basis of his reputation, or his thoughts as recorded in the printed word, or his disembodied voice as it comes out of a loudspeaker. Television makes the candidate of today a human being at one's elbow, who is going to be judged on the same terms as a man greets any new acquaintance. (Gould 1972:21) Since then, television's image-making power is thought to have been influential in most elections, particularly in the Nixon-Kennedy debates, in Nixon's return to politics in 1968, and in Carter's campaign of trust and honesty in 1976. And yet the search for clear evidence of television's impact has been mostly futile. As Joseph Wagner's (1983) review of research indicates, except for event-specific or group-specific phenomena, the quantitative literature has for the most part confirmed the "minimal effects" thesis. Beyond this, content analyses of television and newspapers suggest that the two media present very similar images of candidates (Hofstetter, 1976; Meadow, 1973; Evarts and Stempel, 1974; Patterson, 1980). Voters' perceptions of the personal qualities of candidates do not appear to vary with the particular mix of their information sources (Patterson and McClure, 1976; Miller and Jackson, 1973). However, while voters may hold similar images of candidates regardless of how they obtain political information, the importance of candidate images-relative to other information-may be greater for voters who depend upon television. Despite similarities with other media, television by its nature provides a qualitatively different product. It provides the candidate as a person. This is a function of the visual and actual nature of television's content, and is reinforced by practices of its news organizations and personnel that serve to downplay cognitive content. Doris Graber's analysis of campaign news on television and newspapers supports this view: The skimpiness of television issue coverage, particularly the dearth of quotes by candidates, meant that people who relied primarily on television for campaign information learned little about the candidates' stands on issues and even less about the candidates' priorities. This left the television viewer with information weighted heavily in favor of using characteristics of the man, rather than issue positions, as voting criteria. (Graber, 1976:300301). Wagner (1983:415-426) provided evidence that the television's slighting of issues leaves the television-dependent voter less able to discriminate between candidates on the basis of issues (see also Clarke and Fredin, 1978). Thus, voters choose as best they can. Television makes information about candidates personal qualities cheaper to obtain than This content downloaded from 207.46.13.115 on Sat, 08 Oct 2016 05:08:45 UTC All use subject to http://about.jstor.org/terms

The adult respiratory distress syndrome. Cell populations and soluble mediators in the air spaces of patients at high risk.

Abstract: In order to better understand the modulation of polymorphonuclear neutrophil influx into the lung during the development of the adult respiratory distress syndrome (ARDS), we evaluated bronchoalveolar lavage fluids from control subjects (n = 9), patients at high risk of developing ARDS (n = 12), and patients with ARDS (n = 11) for cellular and protein content and capacity to promote neutrophil adhesion to tissue culture plastic. Analysis of the lavage fluids from high risk patients and patients with ARDS showed an 8- to 10-fold increase in the total number of cells, an increase in the percentage of neutrophils present (control subjects = 1 ± 0.4%, high risk = 53 ± 8%, ARDS = 70 ± 7%), and a 10- to 40-fold increase in protein content. The adherence of normal neutrophils to plastic surfaces after pretreatment with either concentrated lavage fluid, ultrafiltrates of BALF, or plasma samples was determined to evaluate the neutrophil adherence-promoting activity of each. Lavage fluid from high risk patients and...

Hyperglycemia, cerebrospinal fluid lactic acidosis, and cerebral blood flow in severely head-injured patients

Abstract: Cerebrospinal fluid (CSF) lactate concentration is known to increase during the acute phase after severe head injury. To determine the influence of glycemia or cerebral ischemia on this lactate increase, we studied 69 head-injured patients aged 28.7 +/- 15.4 (SD) years with a mean Glasgow coma score of 5.7 +/- 1.7 (SD). They were intubated, paralyzed, and artificially respired. We measured lactate and glucose concentrations in ventricular CSF (VCSF), arterial blood, and jugular bulb blood for 5 days. Samples were obtained within 12 hours after injury and at regular 12-hour intervals. These patients were not treated for hypo- or hyperglycemia. Cerebral blood flow (CBF) was also measured within 12 hours and at 12- to 48-hour intervals. Hyperglycemia was found consistently within 12 hours after injury (224 +/- 98 mg/dl, P less than 0.001), and mild hyperglycemia persisted during the entire period of study. The VCSF glucose course was parallel to that in blood (the initial VCSF glucose value was 128 +/- 37 mg/dl, P less than 0.001). The blood lactate value was also elevated during the first 12 hours (4.2 +/- 2.0 mmol/litre, P less than 0.001), normalizing within 24 to 36 hours. The VCSF lactate course was independent from that of the blood lactate value. It was significantly elevated within 12 hours after injury (5.3 +/- 2.6 mmol/litre, P less than 0.001) and remained so during the 5 days of study. A high initial VCSF glucose value was associated with a high initial VCSF lactate value. However, a high VCSF lactate concentration was present even when the glucose value was close to the normal level.(ABSTRACT TRUNCATED AT 250 WORDS)

Self-Directed Adult Learning: A Critical Paradigm Revisited:

Abstract: The phenomenon of self-directed learning has received considerable research attention from adult educators. This review of the literature seeks to analyze and categorize both data-based and concept...

An MRI phantom material for quantitative relaxometry.

Abstract: Most phantom media in current use exhibit T1 relaxation times that are significantly dependent on both temperature and operating frequency. This can introduce undesirable variability into relaxation measurements due to temperature fluctuations, and complicates direct comparison of imagers operating at different magnetic field strengths. Our investigations of a nickel-doped agarose gel system have demonstrated near independence of the proton relaxation rates to a wide range of temperatures and frequencies. We therefore propose the adoption of Ni2+ as a relaxation modifier for phantom materials used as relaxometry standards.

Adrenoleukodystrophy: Dietary oleic acid lowers hexacosanoate levels

Abstract: Adrenoleukodystrophy (ALD) is an X-linked disorder characterized by demyelination, adrenal insufficiency, and accumulation of saturated very-long-chain fatty acids (VLFA), particularly hexacosanoate (C26:0). We treated 5 patients with adrenoleukodystrophy (3 males and 2 symptomatic female carriers) for 6 months with a diet enriched in oleic acid (C18:1) and moderately restricted in C26:0. Elevated plasma and erythrocyte levels of C26:0 decreased in a time-dependent manner during treatment. Total plasma C26:0 concentration was lowered by 50 +/- 9% (p less than 0.01); it became normal in the female carriers. The total erythrocyte level of C26:0 decreased (44 +/- 5%; p less than 0.001) into the normal range in all patients. Significant decreases were noted in the saturated VLFA composition of plasma and erythrocyte sphingomyelin and erythrocyte phosphatidylcholine during dietary treatment. In general, decreases in saturated VLFA levels were accompanied by increases in monounsaturated VLFA levels, while total VLFA values did not change. This novel approach to the treatment of adrenoleukodystrophy, in which there is an exchange of monounsaturated VLFA for the more toxic saturated VLFA, may prove clinically beneficial in this disorder.

Kalman filtering approaches for solving problems in analytical chemistry

Abstract: The application of the Kalman filter to the solution of a variety of problems in analytical chemistry is reviewed. Five examples are selected from the literature to illustrate the use of Kalman filtering techniques for obtaining least-squares estimates fo several parameters of analytical importance. These examples include multicomponent curve resolution and concentration estimation, correction for variable background responses, calibration with drift compensation, and estimation of kinetic parameters for first-order reactions and for heterogeneous charge-transfer reactions. An adaptive Kalman filtering technique is required for the solution of the background correction problem, and the extended Kalman filter algorithm is required for the solution of the nonlinear kinetic problems. For each case, the results that were obtained are summarized, and some advantages of Kalman filtering over traditional least-squares approaches are discussed.