Showing papers by "University of Pittsburgh published in 1987"

An analysis of 5'-noncoding sequences from 699 vertebrate messenger RNAs

Abstract: 5'-Noncoding sequences have been compiled from 699 vertebrate mRNAs. (GCC) GCCA/GCCATGG emerges as the consensus sequence for initiation of translation in vertebrates. The most highly conserved position in that motif is the purine in position -3 (three nucleotides upstream from the ATG codon); 97% of vertebrate mRNAs have a purine, most often A, in that position. The periodical occurrence of G (in positions -3, -6, -9) is discussed. Upstream ATG codons occur in fewer than 10% of vertebrate mRNAs-at-large; a notable exception are oncogene transcripts, two-thirds of which have ATG codons preceding the start of the major open reading frame. The leader sequences of most vertebrate mRNAs fall in the size range of 20 to 100 nucleotides. The significance of shorter and longer 5'-noncoding sequences is discussed.

Heart-lung transplantation.

Abstract: The survival rate (average, 50%) of patients undergoing cardiopulmonary transplantation falls well below that expected for cardiac transplantation alone. We give a broad overview of the various grounds upon which this difference is likely based and discuss recent advances in each area: 1) criteria for the selection of candidates and donors, 2) methods for ex-vivo preservation of donor organs, 3) technical execution of the operative procedure, and 4) prevention of postoperative infection. In connection with the prevention of postoperative infection, we discuss the potential for the development of a chronic obliterative disease that, once established, has proved inexorable. Current efforts are focused on detection when the process is in an early, reversible stage, and on research into causation. (Texas Heart Institute Journal 1987; 14:364-368)

Simulating, analyzing, and animating dynamical systems : a guide to XPPAUT for researchers and students

Abstract: List of figures Preface 1. Installation 2 A Very Brief Tour of XPPAUT 3. Writing ODE Files for Differential Equations 4. XPPAUT in the Classroom 5. More Advanced Diffferential Equations 6. Spatial Problems, PDEs, and BVPs 7. Using AUTO. Bifurcation and Continuation 8. Animation 9 Tricks and Advanced Methods Appendix A. Colors and Linestyles Appendix B. The Options Appendix C. Numerical Methods Appendix D. Structure of ODE Files Appendix E. Complete Command List Appendix F. Error Messages Appendix G. Cheat Sheet References IndexAppendix C. Numerical Methods Appendix D. Structure of ODE Files Appendix E. Complete Command List Appendix F. Error Messages Appendix G. Cheat Sheet References Index.

The market maven: A diffuser of marketplace information.

Abstract: The research focus is individuals who have information about many kinds of products, places to shop, and other facets of the market, and initiate discussions with and respond to information request...

The multicenter aids cohort study: rationale, organization, and selected characteristics of the participants

Abstract: The Multicenter AIDS Cohort Study was designed to elucidate the natural history of the infection causing acquired immunodeficiency syndrome (AIDS), identify risk factors for occurrence and clinical expression of the infection, and establish a repository of biologic specimens for future study. A variety of recruitment techniques, including special assurance of confidentiality, were used to enroll participants. Nearly 5,000 homosexual men volunteered for semiannual interview, physical examination, and laboratory testing in four metropolitan areas. A significant majority of these men in each center (69-83%) reported having 50 or more lifetime sexual partners, and over 80% had engaged in receptive anal intercourse with at least some of their partners in the previous two years. By the time of the participants' initial evaluation (April 1984-April 1985), infection with the human immunodeficiency virus (HIV) had occurred in higher proportions of men in Los Angeles (51%) and Chicago (43%) than in Baltimore/Washington, DC (31%) and Pittsburgh (21%), presumably as a result of the higher number of partners and proportion with whom these men had engaged in high-risk practices (e.g., receptive anal intercourse). Follow-up evaluations are underway in this comprehensive longitudinal investigation of HIV infection.

Critical factors in successful project implementation

Abstract: This paper describes a process used to determine critical success factors that are felt to be predictive of successful project management. Full time managers who have had experience with projects were used to generate critical success factors that they felt to be crucial to successful project implementation. Ten factors were discovered that relate well to previous theoretical formulations in the literature. In addition, these ten factors have been linked together in an interdependent quasi-sequential framework. This research has provided the basis for developing a behavioral instrument to be used as a diagnostic for assessing the status of any project as determined by the ten factor model.

Education and learning to think.

Abstract: The economic and social challenges confronting the nation today demand that all citizens acquire and learn to use complex reasoning and thinking skills. Education and Learning to Think confronts the issues facing our schools as they take on this mission. This volume reviews previous research, highlights successful learning strategies, and makes specific recommendations about problems and directions requiring further study. Among the topics covered are the nature of thinking and learning, the possibilities of teaching general reasoning, the attempts to improve intelligence, thinking skills in academic disciplines, methods of cultivating the disposition toward higher order thinking and learning, and the integral role motivation plays in these activities.

False Hopes and Best Data: Consent to Research and the Therapeutic Misconception

Abstract: To maintain a therapeutic misconception is to deny the possibility that there may be major disadvantages to participating in clinical research that stem from the nature of the research process itself. It could be argued that the research project has been peer-reviewed for scientific merit and approved for ethical acceptability by an institutional review board (IRB), the problem of the therapeutic misconception is not significant enough to warrant intervention. The neutral explainer would be responsible to the IRB and would be trained to emphasize those aspects of the research situation about which the IRB has the greatest concern. This approach might be especially appropriate when the investigator is also the subject's treating physician and the methodology used is likely to be interpreted as therapeutic in intent. The unique aspects of clinical research include the goal of creating generalizable knowledge; the techniques of randomization; and the use of a study protocol, control groups, and double-blind procedures.

The theory of ratio scale estimation: Saaty's analytic hierarchy process

Abstract: The Analytic Hierarchy Process developed by Saaty (Saaty, T. L. 1980. The Analytic Hierarchy Process. McGraw-Hill, New York.) has proven to be an extremely useful method for decision making and planning. However, some researchers in these areas have raised concerns over the theoretical basis underlying this process. This paper addresses currently debated issues concerning the theoretical foundations of the Analytic Hierarchy Process. We also illustrate through proof and through examples the validity or fallaciousness of these criticisms.

How are Foreign Policy Attitudes Structured? A Hierarchical Model

Abstract: It has long been assumed that foreign-policy attitudes of the mass public are random, disorganized, and unconstrained if they exist at all. Further, foreign-policy thinking has not been found to be structured along standard ideological (liberal-conservative) lines, partisan lines, or class lines. We attempt to move the discussion from a question of whether foreign-policy attitudes are structured to a question of how they are structured. We propose and estimate (using a LISREL model) a hierarchically organized foreign-policy belief structure in which specific policy preferences are derived from postures (broad, abstract beliefs regarding appropriate general governmental strategies). These postures, in turn, are assumed to be constrained by a set of core values about the international community.

Cultivation and synchronous morphogenesis of Dictyostelium under controlled experimental conditions.

Abstract: Publisher Summary Cell populations are cultivated for a number of purposes: (1) to maintain strains; (2) to isolate mutants, revertants, or ploidal variants from a parent stock; (3) to harvest large numbers of cells for isolation of DNA, plasma membranes, proteins, and other entities; and (4) to obtain physiologically homogeneous populations of vegetative amoebae that can then be made to proceed synchronously through part or all of the morphogenetic sequence leading to fruiting body construction. To achieve these ends, the myxamoebae are grown axenically or in association with bacteria, on solid substratum or in liquid suspension, clonally or in mass culture. Detailed protocols that cover these exigencies are given. Three methods for strain preservation generally employed: lyophilization, silica gel desiccation and frozen storage. Under optimal conditions, vegetative cell populations harvested from nutrient medium and dispensed homogeneously on a solid substratum can be made to exhibit remarkably consistent morphogenetic behavior in respect to the timing and patterns of aggregation and of fruiting body construction.

The Clinical Picture of Major Depression in Children and Adolescents

Abstract: • Symptom frequency and severity were compared in two sequential clinically referred samples of 95 children and 92 adolescents, aged 6 to 18 years, all medically healthy, assessed with the Schedule for Affective Disorders and Schizophrenia for School Age Children, Present Episode, who met unmodified Research Diagnostic Criteria for major depressive disorder (MDD). There were no significant differences between the two groups in the majority of depressive symptoms. However, prepubertal children had greater depressed appearance, somatic complaints, psychomotor agitation, separation anxiety, phobias, and hallucinations, whereas adolescents had greater anhedonia, hopelessness, hypersomnia, weight change, use of alcohol and illicit drugs, and lethality of suicide attempt, but not severity of suicidal ideation or intent. Adolescents with a duration of the depressive episode of two years or greater had significantly higher rates of suicidal ideation and intent, lethality, and number of suicide attempts than youngsters with depressive episodes of shorter duration. A principal components factor analysis of psychiatric symptoms was carried out in all 296 youngsters evaluated during the same period who met DSM-III criteria for any Axis I diagnosis. The majority had an affective disorder. Factors were quite similar for both adolescents and children and included an "endogenous" and an "anxious" factor, as in many studies of adult depression. In addition, three other factors were found: negative cognitions, appetite and weight changes, and a conduct factor. Suicidal ideation was a component of both the negative cognitions factor and the conduct factor. It is concluded that the similarities across school age in the phenomenology of MDD far outweigh the few differences and that, therefore, developmental changes across this age range, once assessment variance in this age group is controlled for, have only mild to moderate effects on the expression of a limited number of affective symptoms in youngsters with MDD.

Effects of intercistronic length on the efficiency of reinitiation by eucaryotic ribosomes.

Abstract: Simian virus 40-based plasmids that direct the synthesis of preproinsulin during short-term transfection of COS cells have been used to probe the mechanism of reinitiation by eucaryotic ribosomes. Earlier studies from several laboratories had established that the ability of ribosomes to reinitiate translation at an internal AUG codon depends on having a terminator codon in frame with the preceding AUG triplet and upstream from the intended restart site. In the present studies, the position of the upstream terminator codon relative to the preproinsulin restart site has been systematically varied. The efficiency of reinitiation progressively improved as the intercistronic sequence was lengthened. When the upstream "minicistron" terminated 79 nucleotides before the preproinsulin start site, the synthesis of proinsulin was as efficient as if there were no upstream AUG codons. A mechanism is postulated that might account for this result, which is somewhat surprising inasmuch as bacterial ribosomes reinitiate less efficiently as the intercistronic gap is widened.

Inequality and Insurgency

Abstract: Maldistribution of land in agrarian societies is commonly thought to be an important precondition of mass political violence and revolution. Others argue that because of the difficulty of mobilizing rural populations for political protest, land maldistribution is irrelevant except as part of an inegalitarian distribution of income nationwide. These rival inequality hypotheses have significant implications with respect to the kinds of reforms likely to reduce the potential for insurgency in a society. They are tested using the most comprehensive cross-national compilation of data currently available on land inequality, landlessness, and income inequality. Support is found for the argument that attributes the greater causal import to income inequality. Moreover, the effect of income inequality on political violence is found to hold in the context of a causal model that takes into account the repressiveness of the regime, governmental acts of coercion, intensity of separatism, and level of economic development.

Long-term effects of modest weight loss in type II diabetic patients.

Abstract: • Since most obese patients with type II diabetes are unable to achieve ideal body weight, this study examined whether more modest weight losses would provide a long-term benefit. Type II diabetic patients (N =114) were treated in a behavioral weight control program and followed up for one year. Weight loss was significantly correlated with improvements in glycosylated hemoglobin values at posttreatment (r=.55) and one year (r=.51). Patients who lost more than 6.9 kg or had more than 5% reduction in body weight had significant improvements in glycosylated hemoglobin values at one year, while patients losing less weight had nonsignificant changes and those gaining weight had significant worsening. Thus, modest weight loss can have a long-term impact on glycemic control. However, the improvement in glycemic control for a given weight loss was greater initially than at one year, suggesting that energy restriction, in addition to weight loss, may contribute to initial improvement. Neither percent overweight nor diabetes treatment affected weight loss. (Arch Intern Med1987;147:1749-1753)

An L1-like molecule, the 8D9 antigen, is a potent substrate for neurite extension.

Abstract: The 8D9 antigen, a cell surface protein isolated from chicken brain that is related to the L1 class of cell adhesion molecules, is shown to contain an activity that promotes the attachment of neurons and the outgrowth of neurites from chicken tecta and mouse cerebellum. When purified 8D9 antigen is attached to a nitrocellulose-coated substrate, neurons rapidly attach and extend unfasciculated neurites. Little or no attachment of astroglia, oligodendroglia, and fibroblast-like cells to the 8D9 antigen is observed. We propose that a function of the 8D9 antigen is that of a neurite extension-promoting substrate in axon fascicles and in regeneration of peripheral nerves.

Sleep research in affective illness: state of the art circa 1987.

Abstract: Future sleep research in affective illness will probably continue the current evolution beyond cross-sectional to longitudinal studies, and beyond a largely descriptive emphasis to the testing of specific hypotheses and predictions derived from models of the pathophysiology of depression. These models are and will be variously neurochemical, chronobiological, genetic, and developmental in nature. Adequate testing of these models and predictions from them will require the use of pharmacologic and naturalistic probes and the use of sophisticated CNS imaging techniques. These probes will help further characterize the physiology of depression under conditions of disequilibrium or perturbation, such as following sleep deprivation, REM deprivation, phase advancement of the major sleep period, or the administration of antidepressant drugs with specific monoaminergic activity. Concurrently, if one is to understand further whether the sleep abnormalities of depression are part of a larger circadian rhythm disturbance, investigations will necessarily include 24-h measures of sleep-wake activity, psychomotor activity, and probably core body temperature rhythm under constant routine conditions. A complementary point of view would suggest that more intensive investigative efforts be focused on the first 100 min of sleep at night, since it is the first NREM-REM cycle that seems to show the greatest and most specific deviation in depressed patients from normal controls. Efforts to characterize further this part of the 24-h cycle, with respect to age- and gender-related variance as well as responses to physiologic, hormonal, pharmacologic, and naturalistic probes, are strongly warranted.

Cholesterol crystal embolization: a review of 221 cases in the English literature

Abstract: Cholesterol crystal embolization (CCE) frequently presents with nonspecific manifestations that mimic other systemic diseases. The authors reviewed 221 cases of histologically proven CCE in the English literature to define the clinical, laboratory, and pathologic characteristics of this disorder. CCE affected predominantly elderly males (mean age sixty-six) with a frequent history of hypertension (61%), atherosclerotic cardiovascular disease (44%), renal failure (34%), and aortic aneurysms (25%) at presentation. At least one possible predisposing factor was present in 31% and included operative and radiological vascular procedures and the use of anticoagulants. Cutaneous findings (34%) and renal failure (50%) were two of the most common clinical findings throughout the course of CCE. The nonspecific signs and symptoms included: fever (7%), weight loss (7%), myalgias (4%), and headache (3%). Premortem diagnoses were established in 31% of patients most commonly by biopsy of the muscle, skin, and kidney. Mortality was high (81%) and was most commonly due to multifactorial, cardiac, and renal etiologies. The authors conclude that CCE should be strongly considered in elderly patients with atherosclerotic vascular disease who have the onset of renal insufficiency and cutaneous manifestations. CCE may be confirmed by a skin or muscle biopsy.

What Price Spacetime Substantivalism? The Hole Story

Abstract: Spacetime substantivalism leads to a radical form of indeterminism within a very broad class of spacetime theories which include our best spacetime theory, general relativity. Extending an argument from Einstein, we show that spacetime substantivalists are committed to very many more distinct physical states than these theories' equations can determine, even with the most extensive boundary conditions.

Incidence of cleft lip, cleft palate, and cleft lip and palate among races: a review.

Abstract: A review of the literature pertaining to the incidence of cleft lip, cleft palate, and cleft lip and palate in different races is presented. The studies have been evaluated according to the method used to record the incidence rate. Half of the studies include in their base population livebirths, stillbirths, and abortions, or livebirths and stillbirths to record the incidence rate. In addition, in most of the studies, clefts with associated malformations and possible syndromes are included in the reported incidence. There is evidence, however, to suggest that the risk of developing clefts in stillbirths and abortions is three times as frequent as in livebirths and that clefts with associated malformations behave differently epidemiologically from clefts without associated malformations. It is suggested, therefore, that the incidence of cleft lip, cleft palate, and cleft lip and palate should be studied separately for each group, namely for livebirths, stillbirths, and abortions and should be reported separately for clefts without associated malformations, clefts with associated malformations, and syndromes. More research is needed to study the risk of developing clefts among the various groups that exhibit different epidemiologic behavior for each race.

Subtemporal-preauricular infratemporal fossa approach to large lateral and posterior cranial base neoplasms.

Abstract: A subtemporal-preauricular infratemporal fossa approach to remove 22 large neoplasms involving the lateral and posterior cranial base is detailed The areas from which a neoplasm could be removed by this approach included the sphenoid and clival bone; the medial half of the petrous temporal bone; the infratemporal fossa; the nasopharynx; the retro- and parapharyngeal area; the ethmoid, sphenoid, and maxillary sinuses; and the intradural clivus-foramen magnum area The pathology of the neoplasms included benign tumors such as meningioma, malignant cartilaginous neoplasms such as chordoma, and other malignant lesions such as nasopharyngeal carcinoma This approach offers many advantages over other anterior and lateral approaches to the lateral and posterior cranial base: these include minimal brain retraction; direct access to the ipsilateral petrous and upper cervical internal carotid artery; reconstruction of extensive cranial base defects, often with the use of a vascularized rectus abdominus flap; preservation of the hearing conduction mechanism when it is not involved by tumor; and the maintenance of excellent facial nerve function postoperatively The use of an anterior extradural approach (transethmoidal) and of an intradural approach (frontotemporal or retromastoid), either concurrently or separately, is necessary in some patients to effect total tumor removal The most serious complication in this series was the death of a patient due to postoperative infection and bilateral carotid artery rupture, which may have been avoided by the use of a rectus abdominis muscle flap for reconstruction Among the 21 surviving patients, 18 had a good outcome, two had a fair outcome, and one with preexisting neurological deficits had a poor outcome One of the surviving patients with a chordoma died of pulmonary metastases 1 year later, without evidence of local recurrence The length of postoperative follow-up evaluation in these patients is insufficient to make any judgment about the effectiveness of this surgical approach in achieving a cure or long-term control of the tumors described

Sex Differences in Physiological Responses to Stress and in Coronary Heart Disease: A Causal Link?

Abstract: This editorial offers and provides preliminary support for the hypothesis that sex differences exist in physiological responses to acute behavioral stress, which may aid in understanding the enormous sex differences in risk for coronary heart disease Epidemiological data regarding the differential sex experience of coronary heart disease morbidity and mortality are discussed, followed by a meta-analytic review of available psychophysiological data on sex differences in stress-induced cardiovascular and neuroendocrine responses The implications of the meta-analysis for conceptual and methodological issues in psychophysiological research are highlighted

Early experience of tactile stimulation influences organization of somatic sensory cortex

Abstract: Visual experience is essential for the establishment of the cerebral cortical circuitry that allows normal binocular vision. For example, the pattern of right-eye, left-eye dominance columns is permanently altered by simply closing an eye of a young primate1. A critical issue is whether environmental factors also influence the development of other cortical sensory areas. In the present experiments we manipulated the tactile experience of young rats by depriving them of the sensory information that is normally provided by their large facial whiskers. Electrophysiological analyses showed that simply trimming the whiskers from the day of birth results in pronounced abnormalities in the response properties of single neurons in the adult somatic sensory cortex. Thus functional plasticity in response to early experience appears to be a fundamental aspect of cortical development.

The Height and Weight of West Point Cadets: Dietary Change in Antebellum America

Abstract: A decline in nutritional status is inferred from data on the height and weight of West Point cadets in the antebellum period. The decline was geographically widespread and affected farmers and blue-collar workers the most; middle-class cadets did not experience a decline in nutritional status until the Civil War. Nutritional status declined because meat output did not keep pace with population growth. Urbanization and the expansion of the industrial labor force increased the demand for food. However, the agricultural labor force grew at a slower pace, and productivity growth in food production was insufficient to redress the imbalance.

A clash of intuitions: the current state of nonmonotonic multiple inheritance systems

Abstract: Early attempts at combining multiple inheritance with nonmonotonic reasoning were based on straight forward extensions of tree-structured inheritance systems, and were theoretically unsound. In The Mathematics of Inheritance Systems, or TMOIS, Touretzky described two problems these systems cannot handle: reasoning in the presence of true but redundant assertions, and coping with ambiguity. TMOIS provided a definition and analysis of a theoretically sound multiple inheritance system, accompanied by inference algorithms. Other definitions for inheritance have since been proposed that are equally sound and intuitive, but do not always agree with TMOIS. At the heart of the controversy is a clash of intuitions about certain fundamental issues such as skepticism versus credulity, the direction in which inheritance paths are extended, and classical versus intuitive notions of consistency. Just as there are alternative logics, there may be no single "best" approach to nonmonotonic multiple inheritance.

Rank generation, preservation, and reversal in the analytic hierarchy decision process

Abstract: Decision making has the objective of finding the best alternative or set of alternatives by considering a number of goals, objectives, criteria, competitors, and other important factors. The analytic hierarchy process is a decision aid used to assist a decision maker in sorting out the complexity of a decision problem and making use of his or her judgments. A decision maker must be assured that the arithmetic operations of any such decision process are the right ones—that they surface the correct ranking and values of the alternatives and preserve or alter ranks appropriately when new alternatives are added or deleted. In this paper it will be shown that with absolute measurement, rank always is preserved, with relative measurement, rank changes with nspect to scveral criteria only because of the structural dependence (involving both numbers and measurements) of criteria on alternatives. A discussion of the effect on rank of replicas and near replicas of the alternatives also is given.